It’s a rare boring day at Torchwood. The group is playing a makeshift form of basketball as Ianto enters. They soon finish up and exit to get drinks, leaving Ianto alone. He orders a couple of pizzas and soon after, Dr. Tanizaki, a Japanese cyberneticist arrives.
Ianto escorts him down to the lower levels of Torchwood and shows him a cyberwoman – half human, half mechanical. Her name is Lisa and she is Ianto’s girlfriend that he rescued from the destruction of Torchwood One during the Cybermen invasion. The Cybermen were desperate for troops so they started converting humans instead of transplanting their brains. The doctor wonders how Ianto knew how to hook her up and it is then that Lisa awakens and tells him that she instructed him on what to do. Ianto wants the doctor to find a way to revert her back to being human again.
They move her up to the autopsy bay and Tanizaki is able to get Lisa breathing on her own. Before they can do anything else, Ianto is alerted that the rest of Torchwood is about to return to the hub to investigate a possible UFO over Cardigan Bay. Ianto sends Tanizaki and Lisa back down to the cyber room while he tries to cover up. As Tanizaki assists Lisa, Lisa turns on him and puts him into the conversation machine and activates it.
Once Lisa activates the machine, Torchwood experiences a power drain. Jack tells Tosh to investigate but Ianto heads them off, claiming the generators have been acting up all day. He tells them he’ll go down and take another look. When he gets to Lisa, he is greeted by the dead Tanizaki, cybernetic parts attached to various parts of him. Lisa claims his “upgrade” didn’t work on him. Ianto disposes of the body.
Tosh find two life signs in the basement after the power drain. They know one is Ianto, but who is the other? Jack thinks they have been infiltrated and the team arms up. Gwen and Owen go down to find Ianto. Tosh finds that someone has deleted internal CCTV records and removed some images. She does find one of Ianto and Tanizaki.
They enter the conversion room and Owen is astonished, shocked, and dismayed at the sight of the conversion unit. Owen tells Jack who tells them both to get back up to the main floor. Before they can do anything, Lisa knocks Owen out and puts Gwen on the conversation unit. Jack heads down to them and tells Tosh to activate lockdown if he doesn’t hear from her in 15 minutes.
Jack enters and is about to shoot Lisa when Ianto pushes him against the wall. Lisa escapes. Tosh powers down Torchwood and puts it in lockdown just as the unit is about to have its merry way with Gwen. Jack turns his gun on Ianto and the three head up the stairs, an unconscious Owen on Jack’s shoulder.
Jack questions Ianto and Ianto confesses about his relationship with Lisa. Jack is stewed that Ianto hid the conversion unit with Torchwood.
Looks like Lisa wants to convert everyone into her own army. The Lisa that Ianto knows is long gone, the cyberbrain taking over what little personality was left in her. She offers to transplant her brain into his so that they can be as one. When Ianto refuses, she tosses him aside.
Jack confronts Lisa who shocks him to death, as much as Jack can die anyway. It takes him a minute but he gets back up and Lisa shocks him again.
Owen and Gwen hide in one of the meat lockers, one on top of the other. Jack wakes up again and revives Ianto by giving him a princely kiss. Bored, Owen and Gwen go at it, their lips locking. Gwen’s cell phone goes off, alerting Lisa to their whereabouts. They scramble out. As Lisa goes after Gwen, Owen stabs Lisa with a scalpel. This only causes Lisa to pause for a moment.
Toshiko manages to get through the main door before Lisa reaches her. Lisa moves towards Owen and Gwen instead, who hide together in one of the freezers. Jack wakes up again, and revives Ianto by breathing life into him with a kiss, as Owen and Gwen start passionately kissing each other in the freezer. Gwen's mobile phone goes off, alerting Lisa to where they are. Gwen and Owen scramble out of the freezer. When Lisa moves towards Gwen, Owen tells her not to touch Gwen and stabs one of Lisa's unarmored areas with a scalpel. However, this only momentarily disables Lisa.
Jack sprays a “special sauce” on Lisa to lure their pet pterodactyl to some tasty chow. It pecks her to death – or so we think. They all manage to escape the hub. Ianto decks Jack. The hub powers up again and Ianto takes off, everyone else giving chase. A delivery girl enters to deliver the pizza Ianto had ordered and is grabbed by a bloody Lisa.
Ianto grabs a gun, Jack disarms him and turns his gun on Ianto. He tells Ianto to kill Lisa and if he doesn’t, Jack will kill them both. Ianto calls him the biggest monster of them all and runs down to help Lisa.
Ianto finds Lisa dead on the floor, but when someone calls his name, he turns to see the delivery girl. Turns out Lisa transplanted her brain into the girl. He cries but pushes her away and pulls his gun on her. She tells him they can both be upgraded and that is enough for Ianto to shoot her dead.
Returning to work the next day, Ianto eyes Jack, who simply nods and the team get back to work as usual.
Not the best episode I've seen but they can't be all homeruns.