Gwen's most recent encounter with an alien is going to make her wedding a memorable one. Just before meeting her girlfriends for her hen night, she is bitten by an alien. The bite seems inconsequential but she wakes up the next morning quite pregnant and appears to be ready to give birth. She has a lot of explaining to do - to Rhys, her parents, his parents - but she flatly refuses to cancel her big day. As the rest of the Torchwood team try to determine exactly what the culprit might be, there's a woman at the wedding who is very interested in Gwen's condition: the unborn alien's partner who is there to collect the soon-to-be-born creature.
—garykmcd