When the Doctor decides to trace an anomalous energy signature on twentieth century Earth, he stumbles into an assassination attempt. Gangland thugs are trying to murder a seemingly innocent shopkeeper, and it’s only the intervention of the Doctor and Ann Kelso – a WPC who happens to be on the scene – that prevents a tragedy. But why do the gangsters want the shopkeeper dead? And what does this have to do with alien technology? The first stages of a grand conspiracy are about to be revealed. And finding the answers will take Ann Kelso on a journey like no other.