Thick black clouds are blotting out the skies over Cardiff. As twenty-four inches of rain fall in twenty-four hours, the city centre's drainage system collapses. The capital's homeless are being murdered, their mutilated bodies left lying in the soaked streets around the Blaidd Dwrg nuclear facility. Tracked down by Torchwood, the killer calmly drops eight storeys to his death. But the killings don't stop. Their investigations lead Jack Harkness, Gwen Cooper and Toshiko Sato to a monster in a bathroom, a mystery at an army base and a hunt for stolen nuclear fuel rods. Meanwhile, Owen Harper goes missing from the Hub, when a game in Second Reality leads him to an old girlfriend... Something is coming, forcing its way through the Rift, straight into Cardiff Bay.