It sounds like yet another of the cheesey touring thrillers which pepper the summer theatre schedules.

But Dangerous Obsession, a play which has stood a 20-year test of time, promises superior thrills, relative psychological realism and some fine acting courtesy of the Ian Ogilvy-led cast.

Best-known for taking over Roger Moore's halo to star in the popular TV series The Return Of The Saint, Ogilvy has since worked extensively in West End theatre and won awards for his acting in America.

Coughing politely at the play publicity's description of him as "one of Britain's most suave and dashing actors", he nevertheless accepts his current role is "not really what people expect from me - I'm usually light comedy".

Charged with driving all the action, which he finds "very exhausting", Ogilvy plays the troubled intruder in a luxurious Georgian house as Dangerous Obsession plays upon our fear of being watched.

As Sally Driscoll (Liza Goddard) waters the plants in the conservatory of her luxurious home, she is unaware that a man is watching her intently through the glass. As he makes his presence known to her, she realises he is not a total stranger, though perhaps her husband has more cause to remember him.

And when the visitor locks the door and slips the key into his pocket, it becomes clear this certainly isn't going to be a social call.

"It's really one man's search for the truth," says Ogilvy of the NJ Crisp play, which was filmed as Darkness Falls, starring Ray Winstone and Anita Dobson, in 1990.

"My character comes to visit this couple, and initially he appears to be wanting to borrow money from them. But it turns out that what he actually wants is information. There's a lot of rather nasty revenge going on."

Driven by the sharp dialogue and taken at a tremendous pace, Dangerous Obsession is full of the sort of nail-biting moments which can completely silence a theatre.

And Ogilvy knew he was doing his job when one of the stagehands, "toughened by theatre, seen it all", came backstage during one interval, desperate to know what happened next.

"It's very unsettling," Ogilvy says.

"My character knows all about this couple, knows how their house works and where things are. But it's a very short play so when you come out of the theatre you'll still be in daylight."

Ogilvy has also found success as an author of late, having swapped the "gently comic rural novels" he used to write for adults for a hero called Measle Stubbs, pitched squarely at the Harry Potter market.

There are three out at the moment and the fourth, Measle And The Slithergoul, will be out in October.

"They're set in the magical world but unlike Harry he doesn't have any powers, " says Ogilvy. "So he has to use his wits and ingenuity to get out of these appalling situations which people keep trying to get him into."

Starts at 7.45pm, Thurs and Sat mats 2.30pm. Tickets cost £15-£24, call 08700 606650.