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The Eternity Trap was the fourth serial of series 3 of The Sarah Jane Adventures. It was written by Phil Ford and directed by Alice Troughton. Because filming took place during his GCSE exams, Tommy Knight sat out this serial, with the reason given for Luke's absence being that he was studying at home.[1]


A haunted house, mysterious whispers and secrets in the shadows attract Sarah Jane's attention. When Professor Rivers and the gang investigate an old legend, a monstrous creature appears in the night. The terrifying grasp of Erasmus Darkening reaches out from centuries past. Sarah Jane and the gang discover the secrets of Erasmus Darkening, but are they too late? Ghosts from the past rise up and the quest to find the missing children reaches a climax. It seems that nothing can stop the ancient alchemist's rise to victory.


Part 1[]

Professor Rivers tells the story of a haunted manor. She speaks of Lord Marchwood and how he employed Erasmus Darkening. Marchwood thought Erasmus could make gold out of nothing. His two children, Elizabeth and Joseph, spy on Erasmus and they vanish for eternity.

Rivers is telling the story to Sarah Jane, Clyde, Rani and her assistant Toby. Luke is at home as their standby lest something goes wrong. Sarah Jane separates and finds a book on the history of the manor. She turns from the book case where she is reading, and behind her, the books move. Clyde and Rani go outside and find a shed and a fountain. The fountain ceases flowing and wet footprints appear in the shed. They hear a young girl cry. It stops as Clyde pulls a sheet from a mirror. A man's face appears in the mirror. They run back to the manor to find Sarah Jane.

Meanwhile in the control room, the camera in the playroom cuts out. Rivers goes to investigate. Abruptly, the nursery monitor starts to play. Seconds later, Rivers vanishes.

The gang go to investigate and find all the toys have come alive. On the mirror in the room, a message appears: "Get out". Clyde and Rani explore and find a secret passageway leading to Erasmus' lab.

Meanwhile Sarah Jane goes outside. She finds a creature with red eyes in the bushes. It advances on her. Lord Marchwood's ghost manifests and he fights it off. Clyde and Rani find a computer, then turn around to see Erasmus Darkening.

Part 2[]

Lord Marchwood arrives with his children to rescue Clyde and Rani. Sarah Jane hears a recording of Professor Rivers saying, "Sarah Jane help me", over and over. Then she sees her. Rivers warns her, "He is coming for you", and disappears. Sarah Jane reunites with Clyde and Rani and they find Lord Marchwood. Sarah Jane believes they are not ghosts. Toby, Sarah Jane, Clyde and Rani discover all the people that have disappeared, except for Professor Rivers who hasn't been absorbed yet. Erasmus arrives and they all disappear.

Erasmus tells them he will come for them all. Sarah Jane and Toby investigate Erasmus' secret chamber while Rani and Clyde distract Erasmus. Toby tells Sarah Jane of a creature who used to come into his room and watch him every night. Rani and Clyde are chased by something into a game room. When all the games start playing by themselves, they run outside and are locked out.

Sarah Jane and Toby find Erasmus' machine. Sarah Jane suspects Erasmus was trying to get home to another galaxy with the machine. The machine malfunctioned and all the people that disappeared were trapped between dimensions. Clyde and Rani run into the pavilion. Sarah Jane and Toby are interrupted by Erasmus. Sarah Jane works out that the machine is giving Erasmus and all the people that disappeared eternal life. She also works out the creature that attacked her earlier came through the machine. Lord Marchwood again rescues Clyde and Rani. Sarah Jane, Clyde, Rani and Toby reunite with Lord Marchwood. Sarah Jane comes up with a plan to stop Erasmus. Erasmus is destroyed and Professor Rivers is returned. Sarah Jane destroys Erasmus' machine with her sonic lipstick. Sarah Jane, Clyde and Rani say goodbye to Professor Rivers and Toby.

Rani declares that this must be the end of the haunted house dealings. Clyde quickly rebuffs her and says that there were never any ghosts in the first place. He asks Sarah Jane if there really are no such things as ghosts. Sarah answers, "That's right... No such thing as ghosts." Her voice slows and becomes hesitant as she peers up at the manor, seeing something peculiar from up above, before slinking into her car. As the trio drive away, Lord Marchwood and his children watch from the window.



General production staff

Script department

Camera and lighting department

Art department

Costume department

Make-up and prosthetics


General post-production staff

Special and visual effects


Not every person who worked on this adventure was credited. The absence of a credit for a position doesn't necessarily mean the job wasn't required. The information above is based solely on observations of the actual end credits of the episodes as broadcast, and does not relay information from IMDB or other sources.







  • When Rani and Clyde hole up in the manor's tool shed, Clyde says "It's not exactly the Alamo".



Story notes[]


  • Part 1 - 1.14 million viewers, with an AI score of 86. (DWMSE 28)
  • Part 2 - 0.93 million viewers, with an AI score of 86. (DWMSE 28)


  • The faceless being that Toby saw as a child was the Trickster.
  • Some people believed that Erasmus Darkening may have been a Time Lord. Sarah commented on Darkening's manipulator having TARDIS-like qualities. Clyde made reference to some aliens looking human and used the Doctor as an example. He seemed obsessed with living forever as if he were a Time Lord on his last regeneration. His clothing was suggestive of Time Lord clothing. The counter-argument is that the Doctor has indicated that he "would know" if there were any other Time Lords still in the Universe. Erasmus was, however, trapped between dimensions, which it is hypothesised may have "hidden" him. In The Day of the Doctor, however, it was revealed that Gallifrey was not destroyed but moved to a parallel pocket universe so the idea that Darkening might be a Time Lord is still a possibility. The actor who portrayed Darkening, Donald Sumpter, later appeared as Rassilon in the television story Hell Bent.

Filming locations[]

  • The Haunted House in the episode was previously used in Series Four of Doctor Who in Forest of the Dead.

Production errors[]

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • In part one, when the Professor is taken, her scream can be heard, but the cameras she is using have no audio, as she earlier uses her radio to talk.


Home media releases[]

DVD releases[]

  • It was released in the Complete Collection Series 1-5 boxset release (Region 2 release: 6th February 2012).


External links[]