From the internationally bestselling author of The Book of Doors and The Society of Unknowable Objects comes a gripping speculative thriller in which a disgraced detective is recruited into a secret government project on a remote island lighthouse—where the impossible science of time travel is used to solve the crimes that justice forgot.

Jack Fletcher was one of the Metropolitan Police’s finest detectives—until he wasn’t. Three years into a prison sentence for a crime he takes full responsibility for, Jack is offered a way out: agree to work on a classified government project for one year, and he will walk free. He feels he deserves his punishment. But what they’re offering…it might just help take some of the red out of his ledger.

He is flown by helicopter to a remote lighthouse on a desolate island somewhere in the North Sea, where a small, secretive team has been doing something that should not be possible. Something that could change everything. Led by the brilliant and eccentric Professor Tim Goldsmith, the group has cracked the science of time travel—and they are using it to go back and witness the crimes that left victims without justice and killers without consequence.

For Jack, a man haunted by the cases he couldn’t close and the faces he couldn’t forget, it feels like a second chance he never expected and doesn’t quite believe he deserves. With the ability to revisit the past, every cold case becomes solvable. Every buried truth becomes retrievable.

But time travel does not stay secret for long. The people who want to exploit it are powerful, well-connected, and ruthless—and Jack is about to discover that the closer you get to the truth, the more dangerous the truth becomes.

Pulse-pounding and impossible to put down, The After Witness is a thriller about guilt and justice, the crimes that define us, and whether going back to fix the past is ever really the same as making things right.