A blizzard traps eight people in a hotel in Agatha Christie's classic thriller The Mousetrap . They are a peculiar lot: a newlywed couple, a prickly older woman, a flamboyant architect, a retired military man, an enigmatic girl, an unexpected foreigner, and a police detective. Among them hides a murderer on the run who has just killed a child, and could strike again any time. The world's longest-running play, set in 1952, has made hundreds of thousands of people scratch their heads until the end. South African director Alan Swerdlow says it's now Hongkongers' turn to guess. He brings the classic whodunnit to the city next month - with a fresh interpretation. The Mousetrap has remained popular for so long because it is so well constructed, with a terrific twist quite unlike Christie's other works, Swerdlow says. "It was one of the first murder mysteries really to explore the psychology and motivations of a killer. It is really CSI [in] Berkshire 1952." "World's longest-running play opens in Hong Kong" Video by Hedy Bok He says while his production is truthful to Christie's intentions, it is in no way old-fashioned; or as he put it, not to be "dried out and stuck behind glass" like a "museum piece". Swerdlow uses actors of the ages Christie specified in the script - London productions since the 1960s have employed older actors. "This decision brings a different energy to the piece and makes it more believable," he says. Some characters have also been reinterpreted, making the story more complicated and challenging for the audience members' inner detectives. For example, Swerdlow redrew the character of Miss Casewell, who is traditionally played as an aloof and quite aggressive woman, as somebody restrained and quiet. In this production, Miss Casewell "spends more time observing than shouting", Swerdlow says. "It makes the character more intriguing than forthright. You will want to work out what the meanings are hidden between lines, and what is going on in her mind, through the body language and facial expressions." For Swerdlow, the most average characters, such as the Ralstons who run the Monkswell Manor hotel, are far more difficult to portray than villains. "They are straightforward, ordinary, middle-class newlyweds," he says. "It is a big challenge to make the characters fully-rounded and believable." The Mousetrap is not deadly serious, but rather like "a guessing game". Swerdlow keeps it light by leaving Christie's dry English sense of humour and use of stereotypes untouched. He says the playwright knew exactly when to give the audience a break after moments of unbearable tension. "One of her favourite comedians is Mr Paravicini, the funny foreigner," he says. "He acts like a truth teller, a court jester who has a licence to say things that other people cannot." There are three big clues in the play if the audience is listening carefully, Swerdlow says. "Even so, there's always a gasp from the audience when the murderer is revealed every night," he says. "Christie keeps on surprising us." The Mousetrap will be staged at HKAPA from October 9 to 14. Tickets are HK$350-HK$950 from HK Ticketing.