We’ll never grow tired of mystery stories, and there’s always room for a comedy musical too. With a silly-sounding set-up, a smattering of character tropes and some powerful singers among its cast, The Detective’s Demise makes a credible stab at skewering both… but the format calls for a quick-stepping caper, and the delivery’s more Miss Marple.

There’s a lot here to recognise and to enjoy. We’re in a country-house drawing-room, where a group of feuding relatives have gathered for a party. The victim Ben, who comes happily back to life for flashback scenes, is splendidly arrogant; another of the guests is subtly but perpetually drunk. The songs are tuneful and catchy, and their themes – such as a relationship that’s definitely platonic – successfully impart a humorous twist to classic mystery vibes.

As the title suggests, Ben used to be a detective, but that matters strangely little to the plot; beyond a couple of fleeting references to past cases, he might as well have been an accountant. Similarly, the crime scene is a murder-mystery party, and everyone’s in themed fancy dress – but nobody really mentions that, and the ensuing visual humour goes nowhere. The title and the set-up promise a feast of genre-loving in-jokes, but the storyline and music don’t deliver.

And, one bravura opening number aside, it’s painfully slow to get going. The scene is set with a lump of spoken exposition, and an uninspiring song which methodically poses five questions to each of five suspects (although, to be fair, they do fast-forward past a few). Overall, this part just needs to be sharper and snappier: losing a couple of bars of filler music, or getting into position just a few beats earlier, could really lift the energy of the opening act.

The denouement’s more satisfying though, as is the poignant 11 o’clock number that precedes it, and like all good detective stories the clues have been planted in plain sight. There’s some witty choreography, a few entertaining sideways glances at their own production values, and an excellent recurring joke around a character whom everyone ignores. If they can raise the whole production to the level of the best bits, it will be well worth the time to investigate.