The Climber

Six flats in one night, high up in a tower block, and the burglar got in and out without a sound. Four hundred pounds is the haul, the kind of money that says professional rather than desperate. The obvious suspect is Keys, a known cat burglar, except Keys has a broken leg and cannot climb a staircase, let alone a tower block. But the team is stuck until someone notices the other half of the household: Keys's son Lee, who has suddenly acquired enough money to buy a pony. Nobody in that family has the cash for a pony.

Elwyn Jones and Allan Prior wrote this one, John Black directed, and the plot turns on the oldest trick in the book: the suspect you cannot watch, so you watch the suspect's son instead. Lincoln gets the undercover job. Peter Clough's Lincoln is a fine choice for it, the kind of officer who can stand in a street and be mistaken for part of the furniture. Hawkins and Grant run the case from the station. The case turns on money that has no right to exist in that household, and the team knows it. John Bennett's Keys limps through it on the injury that should be his alibi, Albert Welling's Lee has the pony money and the wrong answers, and Meryl Hampton's Dawn and Denis DeMarne's Davis orbit the family like neighbours you never quite trust.

The tower block does the work of a whole set: six doors, one climber, and a building full of people who never saw him. The episode is anchored by a lovely piece of reasoning about a broken leg and a pony. It is the sort of detail that makes the show feel true. Crime in this world is not grand. It is six flats burgled for four hundred pounds, and a kid who suddenly had pony money.