Quarry

Frost is struggling — alone, plagued by unsettling dreams, still not right after the year he has had — when he finds himself back with DC Clive Barnard to investigate the murder of Nick Walder, a working-class teenager found bludgeoned in the woods. Nick had been part of a group of hunt saboteurs disrupting a fox hunt organised by wealthy locals, and the investigation peels back layers of class resentment, greed and misdirected violence.

The breakthrough is a hat. Nick was wearing the distinctive blue hat of the saboteurs' ringleader, Tom Cody, on the day he died — Frost realises the killer was aiming at Cody and hit the wrong man. Cody himself is then found shot dead in a country rubbish pile, and a search of his property uncovers drums of stolen antiques. The trail leads to Nick's brother Tony, who confesses in despair: broke, he took a killing contract from an unnamed employer to kill Cody, killed his own brother by mistake, and then finished the job.

The employer is Ruth Ormrod, a wealthy huntress played by Allie Byrne with frosty composure. She commissioned Cody to steal art and antiques to order, some sold on through the art dealer Stephen Milmore — a man with a nice line in sleeping with both sides. When Ormrod learned Cody was pouring his share into the anti-hunt campaign, she ordered him killed. She admits it without remorse: she did it not for the money, but for the thrill of discovering the limits of what she could get away with.

Quarry, written by Christopher Russell and directed by Roy Battersby, is the series' most class-conscious episode to date — a murder that begins in a field full of rich people on horses and ends with a woman who treats killing as a hobby. The episode also lets Frost and Barnard repair their fractured partnership, and plants the seed of a new one: Frost and Shirley Fisher finally begin dating. Michael Byrne's Alex Ormrod, the respectable squire whose family is rotting from within, is the episode's slyest performance.