It's Gwen Cooper's first day on the job with Torchwood. and already things aren't going well. As the team investigates a meteor that has crashed on the outskirts of Cardiff, Gwen inadvertently releases a gaseous life form that can take control of a human host.

The unfortunate host for the life form is a young woman, Carys, who uncontrollably becomes a sexual predator after she is taken over. Good news for her that she is right outside a nightclub full of able bodied men. It doesn't take her long to get one of those men to follow her into the restroom where the pair waste no time having sex. Just as things really heat up, the man suddenly disintegrates and is absorbed by the satisfied Carys.

The Torchwood team spends a little time picking on Gwen for her screw up, but a report of the mysterious disintegration soon comes in. Seems a naughty club owner put a camera in the bathroom and caught the whole thing on tape. A little investigation leads them to more camera footage of the gaseous life form taking its host. Gwen now feels responsible for the death.

As the team begins to track the girl down, Gwen realizes she is the only one on the team with a social life while the others spend all of their time working.

Just as Carys is about to satisfy her unnatural carnal desires again, the team burst in and capture the poor girl. They bring her back to the Hub and stick her in a cell. What Gwen intends as an interrogation, soon turns into a sex romp. However, the life form realizes that a female isn't good enough. It can only feed off the orgasmic energy of a male.

Enter Owen, who promptly finds himself naked and locked in the cell in place of Carys. Apparently the life form has the ability to emit pheromones that cause uncontrollable sexual attraction, and Carys has used this ability t escape her cell. She manages to escape past Jack by threatening The Doctor's hand that jack has been keeping in a jar. She disappears into Cardiff again.

Unfortunately, time is running out for poor Carys. Having an alien life form fighting for control of her body is having a detrimental effect on her. The Torchwood team tracks her to a fertility clinic where she has gone on a sexual feeding rampage. Gwen offers herself up as a host for the life form if it will just leave poor Carys alone. The life form agrees and it emerges in its gaseous state, but Gwen has deceived it and caught it in a stasis field. The team watches it die as it can't survive long in earth's atmosphere without a host.

As the rest of the team do whatever they do with their spare time, Gwen returns to her private life, but the events of the day continue to nag her.