Captain Jack Harkness (John Barrowman) returns to his team in spectacular fashion, walking into the middle of a hostage situation involving his team and an alien Blowfish, shooting the intoxicated Blowfish in the head. At the hub, his team question why he left them, and he simply responds that he belongs at Torchwood. They then are alerted to a death near a multi-storey car park, where the team detect energy from the Rift on the corpse. Jack, to even his surprise, gets a hologram message on his wrist device from a person he recognises, and leaves the team to talk to him.
The person is Captain John Hart (James Marsters), a fellow Time Agent and former lover of Jack. He is responsible for the death, and a public disturbance at a nightclub. After a brief fight at the nightclub, John tells Jack that the Time Agency was disbanded and he has since undergone several rehabilitation programmes, before the team catch up with Jack and are introduced to John. John accompanies the team back to the Hub, where he tells the team of three cylindrical devices scattered throughout Cardiff, which he explains are radioactive cluster bombs, and he requires help to defuse them. Thusly, they split into three pairs: Jack and administrator Ianto Jones (Gareth David-Lloyd) search an office block, doctor Owen Harper (Burn Gorman) and technical expert Toshiko Sato (Naoko Mori) search a warehouse, and police liaison Gwen Cooper (Eve Myles) and John search the nearby docks.
It is clear that John has an ulterior motive; first, he paralyses Gwen and locks her in a crate. He then finds Owen and Tosh, shooting the former in the hip. Finally, he confronts Jack, who realises that the bombs are an elementary 51st century confidence trick. Jack throws the device over the building, and John pushes him off the roof in retaliation.
John returns to Torchwood, where he takes a pyramid-shaped object from the Blowfish in the morgue. The team, including Jack, who survived due to his immortality, hold John at gunpoint, where he admits that the "bombs" will simply triangulate the location of a diamond he stole off a former lover. However, by using the devices and the pyramid, he discovers there is no diamond; John's former lover anticipated dying, and thus set a trap to kill her murderer.
Unwilling to be murdered, John handcuffs himself to Gwen, swallows the key and flees towards the car park. Gwen formulates a plan to use the Rift to kill Hart, but at the penalty of her own life. The team catch John on the car park where he entered and inject him with the team's DNA, thus confusing the device set to kill John. John then agrees to free Gwen and leave, but before leaving, tells Jack that he "found Gray", visibly disturbing Jack, who just asks his team to get back to work.
John Barrowman – Captain Jack Harkness
Eve Myles – Gwen Cooper
Burn Gorman – Owen Harper
Naoko Mori – Toshiko Sato
Gareth David-Lloyd – Ianto Jones
James Marsters – Captain John Hart
Kai Owen – Rhys Williams
Tom Price (uncredited) – PC Andy Davidson
Menna Trussler – Elspeth Morgan
Paul Kasey – Blowfish
Crispin Layfield – Mugger
Nathan Ryan – Victim
Inika Leigh Wright – Hologram Woman
Sarah Whyte – Miss Styles
Writer Chris Chibnall
Director Ashley Way
Script editor Brian Minchin
Producer Richard Stokes
Chris Chibnall (co-producer)
Executive producer(s) Russell T. Davies
Production code 2.1
Series Series 2
Length 50 mins
Originally broadcast 16 January 2008