Dark Room (en Inglés) - Alex North

For DI Andrew Hicks, solving a murder is logical: your first suspicions are usually right.
So when the brutally beaten body of a young woman is found, Hicks immediately turns his attention to the most likely culprit – her possessive ex-husband.
But when a second body is found, similarly beaten, Hicks is forced to think again about his suspect.
As the death toll starts rising, Hicks realises he’s dealing with something much darker – and deadlier – than he’d imagined.
A serial killer is at large – one who revels in chaos.
To stop the senseless murders, Hicks must bring the killer to justice.
But will his own demons stand in the way?