This is circus at its most daring and physically expressive. The Australian circus quartet Casus revives last year's hit show Knee Deep for a limited run at the Riverside Studios. This is an important step for one of the most visually arresting companies out there, and I have no doubt they are destined to become a force to be reckoned with.

All four members focus on their individually honed skills, but also work remarkably well as an ensemble. I was won over, not only by their exemplary skills but also the joy on their faces, holding back the creases of a smile after their acts seamlessly go by.

The audience's gasps, squeals and outbursts of clapping at the end of each sequence frustrated me, but ultimately these momentary lapses in my concentration (and flashes back to reality) were short-lived and I quickly fell back down the rabbit hole. I could happily have stayed down there for another two hours.

The narrative ark is held together via the use of egg cartons that we see projected close up on two screens either side of the square stage. Emma Serjeant highlights the precariousness of their journey, and the relationship between risk and fragility, by walking over the eggs (her speciality is hand balancing).

Jesse Scott flips and dances around an eggcup and bottle as if he were seducing a lover - the complex relationship of the prop and performer finding perfect harmony together. Nantano Fa'anana, defying his Maori like muscular build, is elegant and gentile on the aerial silks, and the newcomer Lachlan McAulay, his graceful acrobatic skills slightly underused, makes up for it with a powerhouse performance on the straps.

The burlesque elements don't really add much to the piece and could do with developing further in order to avoid the risk of becoming a simple showcase of the performers 'other' abilities. No doubt Knee Deep will once again be a hit in Edinburgh this year, and will certainly woo the crowds at the Spiegeltent. I cannot wait to see how the future work of Casus evolves, especially their ability to make such gutsy work look so effortless.

- Bertold Wiesner