ORIGINALLY a cult off-Broadway hit, Be More Chill is very much a music-theatre fan’s musical.

It’s an irreverent and darkly humorous look at teenage angst in a US high school, in particular the travails of Jeremy Heere, a geeky loner who can’t find a way to fit in with his fellow pupils.

Lured into seeking a radical solution, he spends his $400 Bar Mitvzah money on buying an under-the-counter pill that somehow links him into a super-computer that controls his behaviour and makes him “more chill.”

Suddenly attractive to the opposite sex, though not necessarily to the girl he really wants, he embarks on a journey that leads to a better understanding of the value of just being himself.

A corny plot, but an imaginative and deliberately chaotic framework keeps the narrative bouncing along.

More importantly, it provides the vehicle for Joe Iconis’s collection of attractive songs and musical motifs —  most in a bubble-gummy high school rock style — that appear and reappear throughout the show.

Scott Folan — all elbows and knees as he navigates his way from painfully shy neurotic to confident boy about class — makes an entertainingly gawky West End debut in the lead role, yet all the while retaining an underlying uneasiness even when the wonder pill is having its strongest effects.

Stewart Clarke, pantomime-villain-style, is outstanding as the voice of the computer that malevolently rules Jeremy’s movements and Millie O’Connell is a comedic beacon as the bullying but fragile Chloe Valentine.

There’s not a weak link in the small but consistently excellent cast.

While it’s easy to see how it’s all going to end, that’s not really the point. Although Be More Chill makes one or two serious points about our dangerously needy relationship with the digital world, it’s real aim is to provide the audience with a lot of fun and in that it succeeds handsomely.

Runs until September 5, box office: bemorechillmusical.com.

PETER MASON