Spinach is not, claims the press release, a musical or an opera. It is a play where every word happens to be sung. For those for whom the prospect of 80 minutes of nothing but recitative invokes feelings of dread, fear not: Spinach is more of a conventional musical than it likes to admit. More importantly, it’s a classy comedy thriller with great performances from its quartet of actors.

Cassandra Compton (Kate) and Ben Gerrard (Tom) in Spinach at the King's Head, London Photo: Tristram Kenton

Cassandra Compton and Ben Gerrard are engaging and sparky as the couple who awake to find themselves tied up together, with no memories of each other or how they got there. Their attempts to piece together the events of the previous days provide the core of the piece - and it is here where the sung-through nature of the music is most effective, allowing the pair to flit between present and slowly emerging past with a frequency that a musical with standard show numbers would not permit. It’s fun and frenetic, which does much to hide that there’s not a huge amount of story progression going on.

Claire Greenway and Craig Whittaker provide accomplished support, with composer Simon Waters giving both of them solo numbers that would not be out of place in a show that was more obviously a standard musical, and which each deliver with enjoyably infectious conviction.

The denouement of the show’s thriller element may be easy to guess, but when the route to get there is such fun, it’s churlish to quibble. Whether it’s a musical, an opera or a play, it’s good theatre.