In this summer of endless midsummers – seriously, it's like Groundhog Day out there – Simon Evans' ultra stripped-back staging is the seething speed-demon of the pack.

In his compressed version, so compressed it might have been through a car crusher, Evans reminds us that the lovers really are in love, and that, by leaving Athens for the woods, they're risking everything – their lives as well as their loves. Freddie Fox's Demetrius, his nostrils flaring in anger, his jaw muscles pumping like pistons, is determined to have his way – that Suzie Preece's Hermia must marry him or die. Rather than sighing wistfully, Lucy Eaton's Helena looks on the brink of depression.

This is A Midsummer Night's Dream with all the whimsy wrung out of it, real charge thumping through its veins. Such is the rancor of their split, Ludovic Hughes' Oberon spits in his fairy queen's face, and the Mechanicals, performing on pain of death, take their art form as seriously as they can manage. Fox, doubling up as Bottom, is a Tom Cruise type, who treats acting like a martial art. His transfiguration, when it comes, is agonising and ugly. His limbs reshape themselves; his tongue hangs slack; his dick goes up and down like Tower Bridge. He lollops around like the Elephant Man come to fairyland, spluttering and salivating.

Yet all this is done through theatre's rough magic: no set, no lights, no sound, the merest hint of costume. Evans acknowledges the play for what it is, so his cast start sat around a table-read, divvying up parts as the Mechanicals do and checking in with an Arden text.

It's like the grandchild of Peter Brook's legendary white-box Dream. Almost half a century on, Evans takes that empty space and moves it on a notch. His bare stage is a strip of plywood flooring between two audiences, and his forest is left for us to imagine; actors asking us to picture an oak shooting up through the stage. Yet, even as it forges its fiction with one hand, the production undermines it with the other, always tipping us a conspiratorial wink. While the lovers tiptoe reverently around the trunk, Fox's Bottom strides straight through. Hughes conjures an entire wood and its weather system with words, only for Melanie Fullbrook's sceptical Puck to shoot it down with a quizzical look.

That is the ‘magic' of theatre: its doubleness. And A Midsummer Night's Dream, we're told, is a play about what's real and what's not; in which people stand in for fairies and, in this case, awkward audience members for magic flowers. "Me thinks I see these things with parted eye," says Lysander on waking at the end, "where everything seems double." So do we; theatre enchants our eyes like fairydust.

However, all this comes too close to being theatre about theatre about theatre. Evans might refresh our sense of A Midsummer Night's Dream – dousing it with descaler to get back to its truth – but what of that? The play itself has little to say on human nature and, even energised and ardent, it remains featherweight as a fairy's wing. Strip theatre this far back, put everything on the actors, and you need a crack cast. Evans', sadly, are too uneven; just unable to keep the tightrope taut at all times. That lets the air in and, every so often, breaks the spell. Pity. It's almost a dream.

A Midsummer Night's Dream runs at Southwark Playhouse until 1 July.