Anthony Horowitz has no shortage of fans, particularly of his six Diamond Brothers books. Which, on the plus side, means New Old Friends theatre company has a ready-made audience – but equally piles on the pressure to live up to the original.

Happily, this humorous adaptation takes all the best bits from Horowitz’s novel, then adds to it. Alongside the odd minor narrative tweak, there are a few good songs, and an awful lot of doors opening and closing. A cast of four fine actors busy themselves playing 20 different roles, taking us to a dizzying amount of different locations.

For those unfamiliar with the plot – well, you’ll just have to go and see the show, because it’s far too complicated to go into here. Suffice to say, in a fast-paced hour you’ll encounter a very inept private detective, his far cleverer 13-year-old brother, a cast of international criminals, and a box of chocolate-covered honeycomb treats. Plus two dead bodies and some missing diamonds.

Inspired by the kind of film noir detective movie where a box of matches leads you to the next clue, The Falcon’s Malteser is everything the title suggests – light, fun and very silly.

Pleasance Courtyard, 556 6550, until 31 Aug (not 17, 24), 2pm, £10–£11 (£9–£10).