There are some pieces of theatre which are so confident in their concept, so polished in their execution, that if you don't understand them it feels like the fault must surely lie with you. It's tempting, when that happens, to bluff your way through it; to praise the delivery, quietly ignoring the fact that the whole thing made no sense to you at all. But not I, dear reader. I am brave enough to tell you I have absolutely no idea what this piece was trying to say.

Mabel and Garry are frogs; we know this because they wear giant, fluffy frog's heads. Based on their names, we can assume that one is a man and one is a woman, though each is played by an actor of the opposite gender – a fountain of confusion which often left me struggling to follow exactly who was who. The roles they play appear vaguely stereotypical, but that point isn't laboured, and Mabel does seem to have the freedom to improve her lot in life. What is clear is that they are both deeply unhappy: mutually dependent, yet prone to treat each other as children.

Into this domestic disharmony arrives a third frog, Bill. (The blurb says that he's made of metal – but with his prominent glasses and sinister leather gloves, he reminded me more than anything of Herr Flick from 'Allo 'Allo.) We're told that Bill is a puppet: instead of using his actual hands to pick things up, he carries a pair of stiffened gloves, and uses those to manipulate objects instead. David Blindauer is very good at this – and a lot of practice has clearly gone into it – though the effect is rather spoiled by the way that, when more dexterity is required, he just puts down the gloves and uses his hands after all.

The new frog's arrival breaks up the tired domestic pattern, as Mabel falls for their glove-wielding visitor. Before long we're witnessing froggy nookie. Their hands appear to be an erogenous zone.

The physical performance is impressive throughout. Though the characters are fundamentally played as humans, there are bandy-legged nods to the amphibious theme, and I had to admire the commitment shown by all the actors to their thoroughly inscrutable roles. Sometimes decisions feel more random than absurd – as when one of the frogs does a forward roll for absolutely no reason – but on the whole it holds interest, and wrong-foots its audience at every turn.

But what's it actually all about? I'm damned if I know. There seems to be a hint of Prozac Nation to it: the characters talk a lot about prescriptions, and none of them seems entirely well. Mabel appears to achieve self-actualisation by taking off her frog's head – but when Bill does something very similar, it brings him close to death. There are too few points of reference to relate this back to the real world, too little to anchor it among the many serious and nuanced topics it floats around.

In an absurdist piece, of course, you're not supposed to understand everything, and there's a skill and style to the portrayals which can't be denied. But there's a difference between "absurdist" and "incomprehensible" – and for me at least, You Are Frogs fell on the wrong side of the line.