Scarred physically and emotionally when a serial killer throws acid in his face, London DCI Gabriel Markham (Richard Dormer, Game of Thrones) begins an intense manhunt at the scene of the crime and works backward in time to find the killer. Steel your nerves as brutal images rewind in this new twist on a horrific timeline. When and how does a murder begin, Gabriel wonders, and what forces help create a killer or a cop? His unrelenting questions and obsessions test the patience of his good-natured partner, DI Elaine Shepard (Jodi Balfour, The Crown) in their race to catch the culprit.