At fifty, Detective Ali Dawson works for a police department that officially handles logistics and unofficially sends officers back in time to solve cold cases. The unit is nicknamed the Frozen People. Her latest assignment takes her to Victorian London in 1850, where she hopes to clear the name of Cain Templeton, a suspect in a string of murders who was never convicted. While she is away, her son Finn is arrested for a murder in the present day. Griffiths brings wit and warmth to a time-slip mystery with real bite.