Jeremy, the nerdy hero at the centre of this Broadway musical, is worried that he has blown all his barmitzvah money on a TicTac.

Actually the pill is everything its mysterious supplier promises. It is a quantum nano computer that inserts itself into the brain and is an instant antidote to teenage angst. Called a Squip it takes the form of an an inner voice that guides its host through awkward social situations.

In preferences you can allocate a persona to the computer. Jeremy (Scott Folan) chooses Keanu Reeves in Matrix mode (played by Stewart Clarke in suitably long coats) who coaches his host into being cool, especially around Christine (Miracle Chance), the drama student who Jeremy loves, but before his Squip hadn’t the courage to talk to without becoming a gibbering wreck.

Based on Ned Vizzini’s 2005 novel, Be More Chill has all the off-the-wall originality of a cult classic such as The Rocky Horror Show or Little Shop of Horrors. Sci-fi musicals are thin on the ground.

But actually this show belongs to an increasingly common genre. From Dear Evan Hanson, via Heathers, to School Of Rock to name but three, this mucial belongs firmly in the rather overcrowded category of the American high school show.

Yet what on paper looks like an also-ran turns out to be one of the most entertaining shows of its kind. This is partly because Stephen Brackett’s Broadway production is performed by an outstanding young British cast led by the wiry Folan as the gangly geek whose big ambition in life is not to succeed but to survive.

He gets excellent support from Blake Patrick Anderson as his best friend, video game partner and fellow nerd Michael. And among the school’s cooler students the talented Millie O’Connell as the preened and precious Chloe delivers one of the funniest turns currently to be found in musical theatre.

But they key is really Joe Iconis’s pop-rock score which gives Brackett’s production a lift every time the energy levels threaten to sag. Granted, the numbers tend to end with a samey, rousing pitch with fists and palms overreaching for the sky in American can-do optimism.

But the beautifully realised Michael In The Bathroom, tenderly sung by Anderson as someone for whom parties are terrifying, is a classic. And it might just be enough to elevate the whole show to the same level.