Do Me A Favour

The tip-off arrives with a time attached: a haulage lorry is going to be robbed as it leaves the motorway. Barlow has the warning, the location, and a plan. Then the delay happens, whatever it is, and the plan goes soft. A tip-off is only as good as what you do with it, and what the Task Force can do has shrunk with the delay. The delay is never explained, which is right: in police work, delays are a fact of life, not a plot point. They can no longer sit and wait for the robbery to arrive. They have to go out and meet it, and proactive work means choosing, and choosing means guessing.

That shift is the whole episode, the difference between waiting for a crime and chasing one. The show has always been good at the wait before the action, and here the wait is the action. Around the motorway run the usual threads: Evans, Snow and PC Marks on the ground, and further out Frank Mott, Jim Kerr and his wife, and Ann, ordinary people whose lives brush against the operation. But the episode earns its quieter moments too, and the Kerr household gets a little of the show's attention.

Robert Barr and Elwyn Jones wrote it, and Brian Parker directed. Stratford Johns is Barlow, Frank Windsor is Watt and Norman Bowler is Hawkins. David Lloyd Meredith is Evans, Terence Rigby is Snow and Robin Lloyd is PC Marks. Victor Maddern plays Frank Mott, Jon Rollason is Jim Kerr, Chloe Ashcroft is Mrs Kerr and Ann Fairclough is Ann.

The motorway suits the show's pessimism: fast traffic and slow justice, with a lorry somewhere in between that somebody means to stop. The delay means the police have to think faster than the thieves, and there is no guarantee they will. Victor Maddern and the rest of the guests give the road a human edge, which is more than most road-based thrillers manage. And the favour of the title, you suspect, is the one the police are asking of their own nerve.