Episode 5

Harry Pearce attends the funeral of a colleague he believed he understood. A retired MI5 officer, found dead, apparently by his own hand, and Harry mourns him the way the Service mourns its own: privately. Then a journalist arrives with a better story. The officer was murdered, because he was about to sell his autobiography and spill a lifetime of service secrets, and the suicide was a tidy fiction arranged by the people who wanted the manuscript buried with him.

The same crowd, it turns out, had already killed an ex-minister to keep his past under wraps, and now they are hunting the journalist who holds the evidence. He sits under MI5 protection, which is a little like holding an umbrella in a hurricane. Every room the team puts him in becomes a target for somebody, and the body count climbs as the hour goes on.

The episode runs on the show's favourite suspicion: that the Service's own history is the most dangerous thing in it. The dead officer, the ex-minister, the journalist: they are all walking proof that the past does not stay buried, and the weight of that sits on Harry for the whole hour. There is a grim joke buried at the heart of it, too. The dead man's only crime was wanting to be paid for his memories.

Raymond Khoury and David Wolstencroft wrote it, Jeremy Lovering directed. Peter Firth heads the cast as Harry, with Rupert Penry-Jones's Adam, Olga Sosnovska's Fiona, Nicola Walker's Ruth, Anna Chancellor's Juliet, Raza Jaffrey's Zaf, Douglas Hodge's Gary Hicks, Stanley Townsend's Roy Woodring and Andrew Burt's Clive McTaggart around him, while Hugh Simon's Malcolm Wynn-Jones does the worrying in the background.

But what stays with you is the cost of the cover-up, not the cover-up itself. Spooks has buried plenty of secrets in its time. This one digs up the bill and presents it with interest.