Another Life
 Someone has been killing the homeless of Cardiff by chewing out the backs of their necks and eating part of their brains. Gwen and Jack pursue Wildman, their suspect, into a half-finished building site, where he coughs up a starfish-like creature to delay them. Realising that he's been caught and has nowhere to run Wildman deliberately falls off the unfinished building. Owen, who witnessed Wildman's fall, tells Jack and Gwen that Wildman started to scream as he fell, as if he'd changed his mind halfway down. Tosh reports that she's found a cluster of similar deaths around the Caregan barracks, an army training camp in Cowbridge. Owen finds the remains of a burnt-out alien sphere attached to Wildman's spine. Tosh reports that experimental nuclear power packs have gone missing from Blaidd Drwg. Jack and Gwen go to Wildman's flat where they find a woman who identifies herself as Wildman's neighbour, Betty Jenkins. While searching the flat, Jack enters Wildman's bathroom and is attacked by a giant starfish creature lurking in the tub. Gwen's gun has no effect on the creature, and she tells Betty to run, grabs Wildman's electric heater and throws it into the tub, electrocuting the starfish thing. Tosh reports another alien device like the one in Wildman's spinal column was found during the autopsy of Sgt Anthony Bee who was shot dead while trying to steal military equipment from the Caregan barracks. Jack decides to investigate, and Gwen discovers Betty Jenkins was an impostor. At the barracks, Gwen interviews the medical officer who admits that Sgt Bee apparently killed and ate two of his own men before shooting Private Sujit Kandahal in a botched attempt to steal an amphibious vehicle. Jack investigates the contents of Bee's barracks, and finds photographs of Bee scuba diving with his friends: Guy Wildman and Sergeant Sandra Applegate, the blonde woman from the flat. Jack realises that the starfish creature had been guarding something in Wildman's flat. At the flat Sandra has returned and she coughs up a starfish onto Gwen's hand. Jack shoots Sandra, who falls through a window, but he then pauses to stab the starfish creature and get it off Gwen before it can do too much damage; by the time he returns to the window, there's no sign of Sandra's body. Jack returns to the bathroom and finds that the large starfish had been protecting a lead-lined box containing the stolen nuclear packs; he sets off to return them to Blaidd Drwg. Meanwhile Cardiff has been having serious rainstorms, and by the time they get back to the Hub, the Oval Basin is flooded and the water level in the Hub's tidal pool is beginning to rise. Owen has finished decontaminating and apparently gone home. Sandra, realising that her body has been mortally injured by the gunshot wound deliberately steps in front of an ambulance and lets it hit her. Back at the Hub, Owen has been unwinding in a multiplayer online game called Second Reality. Owen finds one of the other players is Dr Megan Tegg an ex-girlfriend who now works at the Cardiff Royal Hospital. Owen goes to visit her and wants to recruit her to Torchwood, as her behaviour in Second Reality has convinced him that she'd be open to the possibilities of alien life. Owen accompanies her to her shift at the hospital and notices Sandra Applegate's name on the in-patient lists, recognises it and decides to investigate, though he does not actually know what Torchwood's current interest in her is. Sandra's X-rays seem to indicate that there is a bullet lodged near her spine but is in fact an alien implant, just like the one in Wildman's body. Sandra then wakes and tells him that she needs Torchwood's help. According to Sandra, she, Tony, and Guy found an alien spacecraft on one of their diving expeditions, and were captured when they investigated. Sandra asks to return to the alien ship to remove the tracker. Owen and Megan drive Sandra out to the Wetlands Reserve, where the alien ship's escape pod is hidden. Sandra tells Owen that the typhoon swamping Cardiff is a result of the ship forcing its way through the Rift. Sandra traps Owen and Megan implanting control spheres in their spines, and the entity controlling Sandra's body vacates it and moves into Megan's. Megan activates a control to reveal an alien life form sitting in a nearby cabinet; this is the true body of the ship's only survivor, a Bruydac warrior. The Bruydac's consciousness has been moving from host to host, trying to find more fuel for its damaged ship. The act of possession burns up human cerebrospinal fluid at an accelerated rate, which is why the Bruydac's hosts had to feed on others to replenish their own. Back at Torchwood, Jack receives a call from Blaidd Drwg, and learns that there are still two nuclear packs missing. Tosh then reports that her weather analysis indicates that something is emerging from the Rift beneath the Bay, causing a localised typhoon that is going to get worse until the source of the disturbance is removed. Jack orders Tosh and Gwen to find Owen and investigate the disturbance under the Bay, using the Torchwood mini-sub; he himself returns to Wildman's flat, hoping to find the two remaining nuclear packs. They aren't there, but Tosh finds that the last person to call Owen's cell phone was Dr Megan Tegg of Cardiff Royal Hospital. Jack goes to the hospital, where he learns that a nurse was recently murdered. Jack goes back to the building site where Wildman died. Jack rushes back up to the eighth floor to find that Megan Tegg has found and retrieved Wildman's briefcase containing the nuclear powerpacks. When she quotes something that Wildman had said in the same circumstances, Jack realises that alien is moving from body to body. It insists that it just wants to escape, but when he refuses to let it get away with murder, it pulls the two remaining nuclear packs out of the briefcase and threatens to smash them together. Before it can do so, Jack shoots Megan in the forehead, killing her. Gwen and Tosh have descended into the Bay and found the alien ship. When Jack kills Megan, Owen revives and attacks Gwen, trying to chew out the back of her neck; fortunately, Ianto arrives just in time and Owen is forced to flee. Jack calls the Hub, learns what's happened, and orders Ianto to restrain Owen and kill him if necessary. While Ianto and Tosh search the Hub for Owen, Jack orders Gwen to fetch some scuba gear and the harpoon gun, and together, they return to the ship. When they arrive, Jack sets the engines in reverse; the ship will tear itself apart backing through the Rift. Jack then executes the Bruydac by shooting its body with the harpoon gun. He then tells Gwen his plan to dispose of the Bruydac's consciousness and he connects himself to the control frame and allows it to implant a sphere in his spine. Gwen calls Torchwood and tells Tosh that Jack has accidentally has a control sphere implanted into his spine. Owen is captured by Ianto, who injects him with a powerful sedative, but the Bruydac has overheard Gwen's call and thus moves out of Owen's body and into Jack's. However, when it opens Jack's eyes, it finds that Gwen has restrained Jack's body in the cage where its original alien body had been resting. Following Jack's earlier instructions, Gwen dons her scuba gear and opens the ship's airlocks and drowns them. Gwen takes Jack's body back to the Hub, where he revives. Unaware that Jack cannot die, the others assume that the Bruydac panicked and incorrectly assumed that he was dead.