AS befits a port city, Hull Truck must go down to the sea every so often.

Moby Dick, Under The Whaleback and John Godber’s April In Paris all took to the waters, while Amanda Whittington’s Ladies’ Day was set in a fish-filleting factory. Now Godber turns nautical once more by adapting Jules Verne’s futuristic sci-fi novel… as an epic musical.

Your reviewer has long called for Hull Truck’s artistic director to risk foregoing the gags just once in his plays, and initially it appeared his vision of Verne might be entirely serious.

Certainly, the topical combination of “destruction on earth, war, financial ruin and a crazed maniac on the loose” had promised a dark drama, and he ends with a warning of the need to respect the sea, but I still can’t fathom what exactly I watched, except a company all at sea on Pip Leckenby’s disappointing set designs.

Unquestionably, Godber wanted to bring out the theatricality as well as the prescience of the story, hence the play’s setting inside a Parisian theatre in 1870 with musical director/narrator Sue Appleby’s Madame Simone hamming up her French accent at the organ.

From here, Joshua Richards’s stentorian Professor Aronnax leads us from his lecture to Captain Nemo’s secret submarine, the Nautilus.

The usual suspects are unwillingly arraigned: Jack Brady’s intemperate harpooner Ned Land, Kim Hardy’s Captain Farragut and Conseil… except that manservant Conseil is now a girl (Heather Peace) disguised as a man who can’t disguise her feelings for the professor… and all because it better suits a musical with a need for some unrequited love interest.

You can understand the dramatic logic, but it has you wondering whether 20,000 Leagues should be closer to the B-movie spoof territory of Return To The Forbidden Planet, rather than its present bedfellow, Lloyd Webber’s The Phantom Of The Opera.

Confusingly, Peace sings a comic finale to the first half, when elsewhere the songs are earnest.

What tone is Godber seeking? You sense the actors are still asking the same question, because they are holding back when they could go as far over the top as Stuart Briner’s songs, which cry out for the big Whitney diva treatment.

William Ilkley’s Shakespearean Captain Nemo is dressed as if for an episode of international baddie duty in Star Trek or Austin Powers, and again you feel a spoof is dying to break out.

This feeling is complete when Conseil is grabbed by the tentacle of what is supposed to be a giant squid: the spirit of The Goodies is suddenly alive, but that surely can’t be the intention.

On the one hand, Godber is drawn to a prophetic tale of desolation and a society on the brink of collapse; on the other, he has chosen the dangerous waters of a musical that turns Verne’s world into a deep-sea diving theatre of the absurd.

This is a very strange sea creature indeed, and ultimately as unsatisfactory as the squid.

20,000 Leagues Under The Sea, Hull Truck Theatre, Hull, until June 19. Box office: 01482 323638.