The concept of a musical set on a submarine entitled Long, Hard and Full of Seamen is promising in itself. Surely there are endless jokes to be had and wildly entertaining plot twists to follow? Unfortunately, Music Box didn’t make full use of this exotic location in their hour-long improvised comedy musical.

Each Music Box show starts afresh. Host and performer Lewis Harrison-Baker is adept at pumping the audience full of energy, encouraging us to meet our neighbours and begin brainstorming ideas. The show’s location and title come from the audience shouting out a range of possibilities – from the mundane supermarket setting to the embarrassing sexual health clinic – until Harrison-Baker draws a line under our mumbling and asks us to vote. It’s a quick decision made by cheering loudly for the idea we most want to see played out on stage. With the submarine setting confirmed, it’s just another split-second before a very quick off-the-mark audience member offers up the show’s title – and the adventure begins.

There’s an inherent freedom that comes with a plot and script-less show: the cast can take us anywhere they like and we will undoubtedly follow their lead. The trouble with Long, Hard and Full of Seamen was that the cast didn’t really take us anywhere – or at least not anywhere particularly daring or exciting. The plot of the evening’s musical amounted to a love triangle between three crew members on board the submarine. It offered plenty in the way of humorous encounters and crude jokes, but I couldn’t help feeling that this story could have been set anywhere, perhaps more suitably in the American high school that one audience member suggested.

On more than one occasion James Witt introduced a luminous green fish finger into the tale, raising our hopes of more exciting events to follow, but the other cast members failed to latch onto this option and instead played a safe bet with the love story. It suggested that perhaps Music Box isn’t all that comfortable with branching out from simpler, formulaic plot lines, which makes this straightforward musical a tad disappointing.

As a cast of strong and capable performers, they transitioned fluidly from scene to scene with little hesitation. Accompanied by a small band consisting of a guitar and keyboard, each number was slick and well-placed, offering amusing segues between scenes. Characters were clear-cut and defined from each other – an essential facet for an improvised musical – with James Witt and Andrew Gentilli in particular contrasting nicely in an amusingly awkward date scene.

Music Box: The Improvised Musical is a light-hearted show with endless possibilities. The cast don’t take themselves too seriously and the focus is definitely on entertaining us. Even with a simple premise, knowing that this is a never-to-be-seen-again performance makes the risk of watching worth it.

Music Box: The Improvised Musical played at the Tristan Bates Theatre. For more information and tickets, see the Music Box Impro website.