In James Bond movies, there are chases; in David Hare's spy dramas, there are strolls.

The circumstances are just as dangerous in Hare's films but his spy, Johnny Worricker, never does anything quite as undignified as running. He saunters at the first sign of trouble. He dawdles from danger. But he is more exciting, frightening, daring and real than Bond could ever be.

The other big difference between Bond movies and Hare's Worricker films, the latest of which was Turks And Caicos (BBC Two, Thursday, 9pm), is that everything happens to Bond while virtually nothing happens to Worricker. Instead, there is a series of conversations about what has happened or what might happen. And that feels real. Real life, even for spies, is just a load of people talking very occasionally interrupted by something happening.

Hare's skill is to capture this while also exploring the great themes of modern espionage and politics. In the first of the Worricker films, Page Eight, broadcast in 2011, the subject was state-sanctioned torture; in Turks And Caicos, the subject is detention centres and how they are paid for and where the profits go. Hare suggests that much of the money from the centres has ended up in hotels on expensive islands - in other words, from prisons for the poor to prisons for the rich.

In the new film, Worricker has turned up on the Turks and Caicos islands after doing a runner from the British authorities at the end of Page Eight but, while there, he has been spotted by an undercover CIA agent. Worricker is played once again by Bill Nighy who is, as usual, a delightful, laconic, lanky stick of coolness; the CIA man is played by Christopher Walken who does that thing of making every word he utters sound sinister. Never, ever let this man read nursery rhymes to your children.

The rest of the cast is just as starry - so starry in fact that a man glimpsed through a window is played by Ralph Fiennes. There is also Ewen Bremner as the wiry Scottish agent Rollo, Winona Ryder as a victim of abuse at the centre of a circle of rich abusers, and Helen Bonham Carter as Worricker's ex-girlfriend Margot Tyrrell.

Margot is now working for Stirling Rogers, the owner of a private equity firm that has investments on the Turks and Caicos islands, and she defends him, at first. "He buys a failing business, he makes it work," she says. "The chariot goes at a certain speed. Peasants fall under the wheels. It happens."

It later turns out Margot isn't as much a fan of capitalism as we think, but her defence of Rogers is one of the best, cynical, sharp sentences in a sparkling, shining script which, combined with subtle, restrained, witty acting, makes Turks And Caicos the best piece of television so far this year. The third of the films, Salting The Battlefield, will be shown on Thursday. Watch it, please, and be amused, engaged, surprised and more than a little bit unsettled.