They're dangling and swinging from the girders of the biomes like strange black insects, the audience craning upwards through foliage as figures swoop against the evening sky.
Forget big feet, red noses and sawdust, this is contemporary circus re-birthed by NoFitState, Britain's leading player in the realm of aerial theatre where old skills with ropes, wires and silks take on a fresh kind of poetry and narrative.
They're at the Eden Project in Cornwall all this month, running workshops and performing on site during the day, then presenting a promenade show called Labyrinth in the evening, written and directed by Firenza Guidi to celebrate the project's tenth birthday.
As we shuffle from giant bubbles through global gardens to the finale in the big top, this extraordinary setting has such presence that even the most assertive circus guerrillas are sometimes swallowed up and overwhelmed by its scale.
From the anti-gravity wonder of the domes, our Ariadne route through the labyrinth is punctuated by surreal tableaux glowing in the undergrowth. Presumably, they're designed to rattle our rationality, and open the cages of our consciousness to new ways of seeing.
We arrive at a big top strung and scaffolded for a spectacle of skills from tightrope and trapeze to acrobalance and aerial hoops. A troupe of shrieking banshees bounce and spasm on bungees, and Gareth Jones's original music is intense, haunting and pulsating.
Times of humour, magic and brilliance streak this show like lightning, but there's repetitiveness about the skills, and bum-numbing hiatuses that mean you stand for nearly two and three-quarter hours.
Lighting is so undramatic you sometimes miss rafter-level action altogether, and promenading means the ground-level stuff may be obscured by a crowd of heads.
But of the companies who were around 25 years ago NoFitState have not only flourished, but worked hard to democratise the art and fulfil their mission "to be the circus everyone wants to join."
To 29 August (01726 811972)