Messiah returns to BBC One with Marc Warren as DCI Joseph Walker, who has finally met his match.

He used to be celebrated for his finely tuned instincts and tenacity of character, but on his latest investigation, his personal demons are haunting him.

DCI Walker recently drove his beloved Palestinian girlfriend, Salma, and her brother, Khalid, from the Gaza Strip through a border checkpoint. Khalid got out of the car and blew himself up, along with scores of innocent people. In the chaos, Salma and Joseph were separated. Now back in England, he's convinced she used him as a pawn.

In a London courtroom, a young girl, Leah, accuses her father of repeated sexual abuse. The case is suddenly thrown by the gruesome and bizarre murder of a key witness and his family, and Joseph Walker is the new boss heading up the investigation.

The defendant, Michael Wallace, and his lawyer, Stewart Dean, provide a firm alibi. Dean's defence case is based on the suspicion that Leah's memories have been instilled in her mind by Daniel Hughes, leader of the New Advent Church.

Meanwhile, a scantily clad girl, Lucy, leaves a nightclub and arrives home – only to find her sister hanging from the ceiling and dressed in men's clothing.

Lucy insists that her sister was a good girl but, too late, Joseph realises the killer must have attacked the wrong woman. He rushes to their house to find Lucy strung up, like her sister, in men's clothing.

Elsewhere, a devout Christian has acid poured into her eyes and Joseph begins to wonder if these are religious hate killings – Hughes becomes an obvious suspect. Finally, when he's least expecting it, Joseph receives a visitor...

Marc Warren stars as DCI Joseph Walker, with Marsha Thomason as DS Mel Palmer and Daniel Ryan as DI Terry Hedges. Rory Kinnear plays Stewart Dean.