The night before her wedding, Gwen is wounded by a man-eating, shape-shifting Nostrovite before Jack manages to kill it. The next morning, she wakes up and is shocked to find herself heavily pregnant. Jack suspects that the Nostrovite impregnated Gwen through its bite, and he encourages her to isolate in the Hub until they can remove the alien egg. Despite her unnatural state, however, Gwen and Rhys are determined to go ahead with the ceremony. But what nobody has realised is that the Nostrovite has a mate -- and it's intent on recovering its progeny from Gwen's belly.