- You may be looking for the titular pathogen.
- 1 Synopsis
- 2 Plot
- 3 Cast
- 4 Crew
- 5 References
- 6 Story notes
- 7 Continuity
- 8 Home video releases
- 9 External links
- 10 Footnotes
What connects strange bird behaviour in the skies above a Madagascan beach to mysterious deaths by a deadly virus that seems to be spreading? And what does a famous British astronaut have to do with all of this? Can the Doctor, Ryan, Graham and Yaz solve this puzzle before it's too late?
Somewhere in space, the spaceship of an astronaut called Adam Lang is malfunctioning. He attempts to try and fix it but it does not work. The capsule starts spinning and turning violently as he tries to deploy the parachute.
In Peru, Gabriela Camara takes her friend Jamila Velez to see a river so they can film it, only to find it has been polluted with plastic waste with birds gathering above, despite normally being beautiful. Late that night, Jamila goes outside her tent and is attacked by an unseen force.
Elsewhere, Jake is drinking in a bar as a breaking news story comes on the TV. It states that Adam is now missing, presumed dead. He is devastated until he receives a text from someone claiming to be Adam, telling him to come and find him somewhere in Hong Kong. Meanwhile, Gabriela wakes up, only to find that Jamila is not there anymore. She goes out to find her and comes across a bird dropping out of the sky. As she goes to touch it, Ryan Sinclair appears and stops her, telling her that something is wrong with the birds.
Jake arrives in Hong Kong. He tries to break into a warehouse where Adam supposedly is but fails to do so. Nearby, Yasmin Khan and Graham O'Brien arrive, brandishing a set of skeleton keys and they follow him in.
By a beach in Madagascar, a laboratory worker called Aramu greets his coworker, Suki Cheng. As they settle down for work, they spot the Doctor sprinting down the beach asking for help. Spotting a body in the water, the three work to get him to ground. The Doctor explains that she usually has help from her friends, but "I gave them all errands."
Meanwhile, Gabriela threatens Ryan about Jamila disappearing, but he denies knowledge as something is wrong with the birds. As Gabriela frisks him for weapons, she introduces herself, supposing Ryan knows her already. He admits he does not and she explains she runs a popular travel vlog with Jamila called Two Girls Roaming. Ryan gathers one of the fallen birds for research as Gabriela receives news that there was an ambulance call-out only one mile away that morning.
Inside the warehouse, Jake questions Graham and Yaz, presuming they had come from the European Space Agency, but they are unaware of Adam going missing. Yaz explains they have been told to find out the reason behind some unusual energy readings coming from the building, unaware that a figure in a full hazmat suit is watching them.
On the beach, the Doctor helps the man out of the water and Aramu identifies his uniform as a member of the US Navy. As the three introduce themselves, the Doctor explains that she has been checking for survivors after an American submarine went missing in the Indian Ocean. As they go to move the man inside Aramu and Suki's lab, he wakes up, begging for help. He gives his name as Zach Olson and explains that his sub got hit and was invaded by something before they could react. As he talks, a stone-like crystalline substance grows and spreads from his hand across his body. It eventually reaches his face, completely covering his features before his body shatters into dust. Stunned, the Doctor tells the others not to be alarmed and she laments not being able to see a connection between the three seemingly unrelated events she has sent her friends to uncover.
Ryan and Gabriela arrive at San Pedro hospital, although it appears deserted. Exploring, Ryan finds another dead bird and he ignores Gabriela's warnings to look inside a quarantined area. Inside, they find Jamila lying on a hospital bed with the same stone coverings as Zach had. Ryan uses his comm dot to contact the Doctor as Jamila starts spasming, her eyes blank. As the TARDIS arrives, the Doctor explains that Jamila is already dead but still being attacked, just as she too disintegrates. Ryan fails to calm Gabriela down as the Doctor realises the severity of the situation.
Meanwhile, Graham and Yaz track down the strange energy readings in the warehouse and discover a room full of strange alien consoles. As Yaz investigates, Adam is illuminated, looking very ill and still in his spacesuit, hooked up to the machinery. Jake rushes over and goes to unplug him, but the others stop him for his safety. Yaz uses her comm dot to call the Doctor but Adam warns them to escape just as two hazmat figures appear and start firing at them. Yaz holds up one of the control panels to the figures and they stop shooting. Sensing a chance, they escape, with Jake helping carry Adam out. However, Jake reveals that he is not an active police officer and so he cannot help more. The Doctor materialises and realises the figures and their weapons are not from Earth.
To escape, she leads her friends, Jake, and Adam into the TARDIS, where Ryan and Gabriela are already waiting. With everyone meeting each other, Yaz refuses to join them. She explains that the device that the aliens did not want to shoot must have been important, so she should be left behind for one hour to get it. Although the Doctor initially declines her, Gabriela volunteers to join, so the Doctor begrudgingly lets them explore.
As the TARDIS takes off, the Doctor performs a medical check on Adam. She receives a phone call from Aramu and Suki, letting her know something else unusual has happened. Landing back in Madagascar, the Doctor goes to use the lab. Graham wonders how Jake and Adam know each other; although Jake says they are married, Adam instead says they have split up because Jake did not put in enough effort in their relationship. As Ryan and Aramu discuss the strange birds like the ones in Peru, a very large flock gathers overhead. Ryan mentions to the Doctor about the one he picked up but Graham shouts to them that Adam's condition is getting worse. Aramu decides to keep watch of the birds.
Back in Hong Kong, Yaz admits to also not recognising Gabriela as they find the control panel from earlier. Yaz notices that it is triangulating signals from two other places, one of which is Madagascar. Briefly hiding from one of the hazmat aliens, it uses the control panels to teleport away. Yaz wants to follow it, to Gabriela's bewilderment.
Ryan hands the Doctor the dead bird and she tells him to dissect it. Talking to Suki about the lab, she checks the equipment and tells Graham and Jake to connect Adam to an IV drip, which Graham has experience with. As Suki collects some of the devices the Doctor needs, explaining she is working on a marine filtration system, the Doctor uses Suki's computer to analyse Adam's readings. Turning quiet, she tells the group that Adam has been infected with an alien pathogenic disease and she does not know how to stop it.
Meanwhile, Yaz insists on following the creature through the teleport. Despite not knowing what could happen, they channel the spirit of Two Girls Roaming to do it anyway. In Madagascar, Graham tries to comfort Jake about Adam's situation. Jake explains that he did not show to Adam's launch to the International Space Station seven months ago as he is not good with emotions, commitment, or foreign travel. Jake admits that knowing that his husband is an astronaut, he believes there is no way he could love somebody like him.
Yaz and Gabriela land somewhere dark but safe and celebrate surviving. Yaz believes they have landed in an alien colony while Gabriela spots some machinery that Yaz realises is part of the missing submarine. In the lab, Suki compares the blood of Adam and the bird, with hopes of using it to engineer a virus. However, the rock-like growths are spreading to Adam's face and the current antibiotics are not working. As Graham alerts the group that the birds are intensifying, Ryan notices his bird is full of plastic inside - something Suki notes is not uncommon in ocean areas. The Doctor realises the alien pathogen is attacking the plastic eaten by the birds and controlling them as if it was a living creature. She quickly dismisses Auton interference and wonders how this relates to the crystals appearing on people. She then realises that microplastics are everywhere, unable to be broken down, and are ingested by humans all the time, which is what Suki and Aramu's lab works to prevent. As the Doctor notices the dead bird's natural enzymes fighting back against the alien pathogen, Suki realises they could make a virus out of it.
Calling Yaz on her comm dot, the Doctor fills her in as Yaz explains where she has landed. However, the Doctor has an epiphany about Suki and her lab being suspiciously over-prepared. Suki says that the Doctor has helped give her more answers than when she experimented on Adam and, naming the infection as Praxeus, she calls it relentless and teleports away. As the birds intensify, the group go to escape, but they are attacked inside. The Doctor retrieves the samples and they all barely escape to the TARDIS waiting outside, although Aramu is unable to follow.
The Doctor locks on to Yaz's comm dot signal to join her but worries about the virus being spread by birds. Adam insists the potential cure should be tested on him but Jake tries to talk him out of it. Meanwhile, Yaz finds a dead hazmat alien and removes its mask to find out it has been fully infected by Praxeus as well. The Doctor uses the antidote on Adam under the promise that the TARDIS will make more if it works. She, Graham, and Ryan leave Jake and Adam inside.
Meeting up with Yaz and Gabriela again, the Doctor reveals they are not on an alien planet, but on an alien-made base deep under the Indian Ocean. They are beneath a natural pollution gyre, which is where Praxeus multiplies best. Ryan questions how it could arrive on Earth at all and the Doctor decides to track down Suki. Inside the TARDIS, Adam promises Jake that, if he dies, he should stop dodging life. Finding a hazmat alien, the Doctor believes it has not disintegrated due to having different biology to humans and wonders if they were experimenting on Adam to find a cure as well. Meanwhile, Adam's life signs turn vital.
Exploring the tunnel, the Doctor's group uncovers the end of a spaceship from which Suki emerges with a gun. She reveals that the hazmat aliens were members of her crew and she is not from Earth either; her planet was ruined by Praxeus so her people were sent off to find an antidote. She found Earth as the perfect lab to test in, although they crash-landed, destroying the ship and spreading the virus further. However, she brags at having found a cure that she has used on herself, although the Doctor reminds her it was made for humans. Inside the capsule, the Doctor tries to bargain with Suki, but Suki finally succumbs to Praxeus and disintegrates.
Outside, the Doctor assembles her friends to find an antidote and they are joined by Jake and a fully-recovered Adam - the TARDIS having worked and distributed a cure. Inside the shuttle, everyone works on the ship, setting its autopilot to the stratosphere with the organic fuel cells loaded with the antidote that will disperse across the world. However, it will also send the Indian Ocean crashing into their base, forcing them out.
Running back to the TARDIS, the shuttle's autopilot fails, but the Doctor knows it will at least take off. As the TARDIS flies away, Adam realises Jake is missing and he arrives on-screen, acting as a manual pilot for the ship. With no other choice, the Doctor gives him his instructions to release the antidote and eventually does it successfully, ridding the Earth of the virus. However, the ship breaks up in space and the Doctor laments being unable to save him as he proves his dedication to Adam. However, as she says it, the TARDIS materialises around Jake, landing him safely inside, and the husbands kiss.
Returning to Madagascar, the Doctor and friends bid a fond farewell to Jake and Adam, telling them to look after the planet. Jake jokes that he deserves a statue for saving humanity and Adam suggests that they hold their honeymoon on Madagascar. Gabriela decides to join them so she can vlog about it and the two groups part ways, safe in the knowledge that no matter how separate they are, the seven billion lives of Earth are safe.
- The Doctor - Jodie Whittaker
- Graham O'Brien - Bradley Walsh
- Yasmin Khan - Mandip Gill
- Ryan Sinclair - Tosin Cole
- Jake Willis - Warren Brown
- Adam Lang - Matthew McNulty
- Gabriela Camara - Joana Borja
- Suki Cheng - Molly Harris
- Jamila Velez - Gabriela Toloi
- Joyce - Soo Drouet
- Zach Olson - Tristan de Beer
- Aramu - Thapelo Maropefela
- Hazmat Alien - Jamie McKee
to be added
- The Doctor has travelled to Madagascar and sent Yaz and Graham to Hong Kong and Ryan to Peru early in the third decade of the 21st century.
- According to Gabriela, Peru has the most beautiful river in the world.
- A beach in Peru is polluted with trash.
- Adam Lang sends Jake Willis a map of his location.
- A naval officer washes up on a beach in Madagascar.
- The Doctor mentions that there is a talking cat in Ontario.
- Gabriela and Ryan track Jamila to a hospital in San Pedro.
- Jake, Graham and Yaz find Adam in an abandoned warehouse in Hong Kong.
- Adam says he enjoyed watching Earth from above, seeing hurricanes and the aurora borealis, and the turn of the planet.
- Yaz is relieved that she and Gabriela didn't teleport into an active volcano.
- Yaz thinks she has found an alien colony which the Doctor reveals to just be an alien construct.
- The Doctor and the whole team investigate the gyre at the bottom of the Indian Ocean.
- Suki Cheng's home planet was infected by Praxeus.
- Jake takes the spaceship into the stratosphere.
- The Doctor indicates she has more than one brain.
- The Doctor gives the team gold stars.
- The Doctor describes herself as "a romantic".
- Gabriela asks if the TARDIS is an optical illusion.
- Jake believes the interior of the TARDIS is a building.
- The Doctor says the TARDIS is bigger on the inside.
- Graham says the TARDIS is a space and time-ship.
- The TARDIS has a holographic screen that can be extended away from the console.
- The TARDIS has a bioreading table to bioread and synthesise the Praxeus antidote.
- Ryan vaguely knows how to dissect dead animals.
- Suki has broad-spectrum antibiotics, a high-power microscope, blood cultures, rapid genome sequencing, a spectrophotometer, and a super fast incubator.
- Suki and Aramu are working on a marine filtration system connected into a Crystal Oceans Initiative; Microversion.
- A pathogen is a microorganism that carries disease.
- Humans are filled with microplastics from ingesting microparticles.
- The bird enzymes are trying to fight back Praxeus.
- Planet Earth is said to inhabit 7,000,000,000 people that are all both separated and connected from the depths of the ocean to the edge of the atmosphere.
- A thief is stealing from Joyce's supermarket.
- Gabriela and Jamila are vloggers on the channel Two Girls Roaming.
- Jake Willis claims to be DI.
- Jake wonders if Yaz and Graham are Interpol or ESA.
- Jake is on a sabbatical.
- The submarine's captain tried to rescue the entire navy team, but succumbed to the virus.
- Aramu and Suki Cheng work in a lab.
- Graham calls Jake Inspector Morse.
- The Doctor thinks Ryan has changed his shower gel because he smells of dead bird.
- Jake and Adam go on their honeymoon at last, with Gabriela following. She wants to vlog about it, which Graham suggests calling Three Idiots Roaming.
- Adam's spacecraft uses Russian and English.
- Gabriela and Jamila speak Portuguese.
- Gabriela refers to Jamila as her "melhor amiga".
- The Doctor mentions the Autons when speculating about the infected birds.
- The aliens use hazmat suits.
Medical injuries and ailments
- The Doctor does an MOT on Adam.
- Praxeus is transferred to humans through contact with infected birds.
- The Doctor informs Adam Lang that his bloodstream has been infected with an alien pathogen.
- The bottled water in the store is from Garwell.
- A football match between Liverpool and Manchester City is playing on the television in a bar.
- BBC News are shown in the bar, mentioning the European Space Agency.
- Gabriela wears a Brasil CBF shirt.
- Gabriela messages some contacts on Reddit to access emergency services and satellites in search for Jamila.
- Jake mentions the International Space Station.
- Zach Olson is from the US navy. He is a naval officer.
- There's a Lido Bar in an alleyway in Hong Kong.
- Adam Lang is onboard a Soyuz spacecraft while calling Control. The spaceship suffers automatic system failure with a failed DMP, unable to switch to ballistic descent and maintain trajectory.
- The number plate of a lorry in Peru is RTE567UYT.
- Jake Willis has a Samsung phone.
- Adam contacts Jake using the number +852 07700 900 781.
- A US submarine went missing in the Indian Ocean.
- Team TARDIS keep in contact with each other using comm dots.
- Yaz talks about unusual energy patterns coming from the warehouse.
- The aliens have set up machinery with a control panel attached to research the alien virus.
- The aliens use special guns.
- The aliens use teleport devices.
- Suki Cheng uses Windows 7 as her operating system on her computer.
- The Doctor uses a Chemical Analyser on Suki's computer to check the chemical data on Adam's Blood Analysis.
- Suki's spaceship has reverse pulse proton engines, organic fuel cells, engine vents, manual bypass, dials, comms, spatial regulators and autopilots.
- Yaz and Graham have a set of skeleton keys that they use at the warehouse in Hong Kong.
- This episode had Doctor Who fans pointing out the parallels between the fictional bacteria Praxeus and the real world Coronavirus. The real virus was discovered in December 2019 and spread in 2020, notably after the episode was filmed.
- The Doctor's opening monologue places Praxeus as taking place "early in the third decade of the 21st century."
- This story marked the first television role in any licensed Doctor Who media given to a Brazilian actress, Gabriela Toloi.
- This story marked the last time Millennium FX worked on an episode of the show.
- Soyuz spacecrafts, like the one seen in the story, exist in the real world.
- The Sea Devils were going to return. This was proven false.
to be added
- As the Doctor is standing in the TARDIS doorway watching Yaz and Gabriela leave, it is obvious that the interior of the TARDIS is just a photo pasted onto the back wall.
- Team TARDIS are investigating the three separate distress signals received by the TARDIS. (TV: Fugitive of the Judoon)
- The Doctor briefly entertains the possibility that the Autons might have taken over the world's discarded plastic. The Nestene Consciousness recently did take over the North Atlantic garbage patch, with ongoing plans for world domination through Bakin Petrochemicals. Rhys Williams took care of this threat in the short term. (AUDIO: Sargasso)
- Team TARDIS use comm dots. (TV: The Tsuranga Conundrum)
- When the TARDIS materialises around Jake, he appears in the interior. (TV: The Parting of the Ways, Let's Kill Hitler, Dinosaurs on a Spaceship)
- Yaz and Graham use a set of skeleton keys at the warehouse in Hong Kong. Previously, the Eighth Doctor carried a skeleton key. (PROSE: Jonah)
Home video releases
to be added
- Praxeus - Overnight Viewing Figures
- Praxeus - Official Ratings