Field Trip (audio story)

 was the fourth and final story of The Twelfth Doctor Chronicles, produced by Big Finish Productions. It was written Una McCormack, performed by Jacob Dudman and featured the Twelfth Doctor and Petronella Osgood.

Publisher's summary
Osgood gets an offer she can't resist when the Doctor drops in – her first flight in the TARDIS!

The Doctor is calling on Osgood's expertise to stop an invasion, but what begins as a fact-finding mission quickly becomes something far more dangerous. Osgood's intergalactic field trip is about to get very hands-on!

Plot
Whilst one Osgood is fetching coffees, the other is visited by the Doctor and eagerly accepts his offer of an adventure in the TARDIS. They travel to Nayspiel, capital megacity of the Alliance, to persuade the politicians not to invade the uncontacted planet Albentsi. Before the Doctor can contribute to a conversation over the Basline Grid, the connection is cut and the Doctor and Osgood split up to chase a man and woman who have been watching them. Osgood corners the woman on a balcony, but the woman uses a gun which makes Osgood fall unconscious.

The Doctor catches up to the man, who tells him to speak with Saynbel before escaping using a personal transporter. He tracks Osgood down to a hotel room where the woman, Saynbel, reveals that she has been working against the man, Blaise of the Lizban Corporation, and wants to save the Albentsians. The Doctor and Osgood go undercover to a casino and meet Lizban to find out where he intends to build the means to connect Albentsia to the Basline Grid. Blaise exposes them and Saynbel extracts them via teleportation, but the Doctor had time enough to set up a trojan device to allow them to hack into Lizban's system.

The Doctor, Osgood and Saynbel take the TARDIS to Albentsi and follow coordinates from Lizban's system with the help of Laysa, a native. They use a signal jammer that Osgood has been working on to block the Basline Grid and order Blaise to leave the planet, but he refuses and they destroy the equipment. Laysa holds Blaise at gunpoint and forces him to leave using his personal transporter, after which the Doctor helps get rid of any trace of alien technology and sets up a shield to keep outsiders from visiting Albentsi. He drops Saynbel off back on Nayspiel and then takes Osgood back to UNIT HQ. The other Osgood enters with coffees and the Doctor and Osgood decide not to tell her about their adventure.

Cast

 * The Narrator / The Doctor - Jacob Dudman
 * Osgood - Ingrid Oliver

Worldbuilding

 * The TARDIS translation circuits are used to translate alien speech.
 * The Doctor mentions his psychic paper as an option to avoid questions if they get caught.
 * The Doctor uses his sonic sunglasses.
 * The Basline Grid is an example of faster-than-light communications technology.
 * Osgood has been working on a signal jammer.

Continuity

 * The Doctor asks Osgood whether she is human or Zygon. (TV: The Zygon Invasion / The Zygon Inversion)