Charity and theatre company The Big House enables care leavers to create theatre. Telling the fascinating, surprising history of Rio Cinema in the immersive Electric, the theatre company has found a laudable, staggering match to its founding ambition. But when you ask your audience to stand in a cool basement for 75 minutes, your offering has to be fierier and more mood-transforming than the drinks they just left at the bar.

I don’t miss my wine yet as I edge down the steps, accosted by a scantily-dressed actress who spits out “what are you doing here? Well, if you like this kinda thing, I guess…” and then, feeling like a shamed brothel-goer (an unfamiliar feeling, I promise), exploring a dingily-decorated, low-ceilinged set of rooms. Wandering around before the show starts, we are teased with clashing characters (a man rubbing a woman’s legs, a girl chatting about an old movie dancer, a strict bespectacled glowering man in the corner) and eras (the unmistakable colour of the 70s, flickering black-and-white projections, the strict dress of early last century). Though it is set in only three rooms, the space is expanded beyond its physical limits, across centuries.

In the main, modern day plot, projectionist William (James Hogarth) timidly charms ex-offender Faith (Henrietta Imoreh) with his dreamy-eyed dedication to movies. At their most captivating, the two pause, quietly step toward each other and wonder (along with the audience) what will happen next… A sudden, heavy movie lecture from William, apparently. Is this diversion from hard-to-handle emotion a defence mechanism belonging to William or the scriptwriter? Throw in an initially comical church congregation, a thuggish, abusive pimp, and the cross-dressing, terrorised brother of Faith’s happy-go-lucky kind of boyfriend, and beautiful simplicity soon gives way to confusion, seriousness to ridiculousness and the Rio Cinema’s history to a bloated plot.

Meanwhile, in unrelated side-stories, a 70s singer is more interested in cash than the harsh brand of feminism that her collective preach, Mrs Ludski (Jasmin Alvarez) is busy founding the cinema, dodging her era’s prejudices and expectations, and – in Electric’s runaway best use of the immersive form – we are taken to a terrifying underground tunnel during an air raid in World War Two. All these tales are moving, rich and believable, but neglected by the script in favour of the modern plot climax, which is static both emotionally and physically. It seems a shame, in an immersive piece, to end with the audience standing in one place for so long that feet begin shuffling.

Electric stays too true to its topic: trailers are often better than movies and the beginning of Electric is better than the show itself. Once the script kicks off, the potential of the space feels more suited to its size: three rooms in a basement. Our intrigue powers down and Electric doesn’t live up to its explosive snippets.  Rather than carefully intertwining a rich array of stories into a stronger tale, too many fascinating ideas – feminism, religion, prejudice – and characters are explored in too short a time, weakening and stretching each thread thin, in a collective mess. The Big House have some untangling to do.

Beautifully acted all round, the cast of Electric win their audience over with charm and enthusiasm. At times, the script jolts the audience’s attention, but without a stronger voltage, more script time and more attention, the best sub-plots and the central relationship of the modern plot fizzle flat, whilst the dull, melodramatic climax is overcharged and overdone.

Electric played at Rio Cinema until 21 November. For more information and tickets, see the Rio Cinema website