Tall tales: Work hard...

That uncomfortable time of year has come round again, when parts of the anatomy normally kept safely hidden in pinstripes are thrust upon the groaning photocopier, and the stationery cupboard is reinvented as a hotbed of passion. Yes, it's time for offices across the country to shred their code of conduct for one night only and get dolled up for the annual Christmas party. At the HQ of 'Product Solutions it's no different. Except that all the 'employees' are actually paying audience members, and the 'heads of department' all actors. In fact, Product Solutions is a fictitious company, and its boozy Christmas party an interactive play.

On arrival each audience member is handed a name badge - so far so accurate - assigning them to a department (Accounts for me), before being taken for a pre-party 'briefing' with the department head. Sadly, my friends and I were lead off by the buxom Helen from HR... and fired. On the bright side, this did mean that we were given some potent shots on the house. (Tip: if you linger there are plenty of leftovers. Trust me, it will make the rest of the night far less painful).

We were then led, in a merry conga line, into the theatre, transformed into a wonderfully tacky party hall, complete with overenthusiastic DJ, shimmering disco balls and the all-important bar. Half price deals pop-up throughout the evening - it's no coincidence that there's a dramatic rise in everyone's level of enjoyment as levels of sobriety decrease. Much like an actual office party, I imagine that the evening would be hell for the teetotal.

The night is organised around a slick(ish) script, and after a David Brent-esque talk from the CEO - outing himself as an alcoholic falling spectacularly off the wagon was a high point - the organised fun started. This was a bit hit and miss: hits included fabulous cabaret acts including some eye-popping pole dancing and full frontal nudity; and misses audience-led party games such as 'pass the balloon'. But it was these moments of embarrassment that made the night work, by creating an awkward atmosphere of faux-camaraderie among the audience, turning the show from performance into painfully realistic office party.

For me, one of the most enjoyable elements of the 'immersive' evening was trying to spot the performers in the crowd. I was convinced that the guy I chatted to at the bar was a fellow theatre-goer, until he suddenly leapt onto the stage to belt out 'Nessun Dorma' as part of the finale, a riotous haze of confetti and dry ice. Although the plot arc feels slightly contrived - it predictably involves an illicit office affair - that is secondary to the experience of being part of something so completely bizarre. So surrender to the weirdness and remember that at least at this office party, you'll never have to see your 'colleagues' again.

Tickets from £35. Pleasance Theatre, Carpenters Mews, N7 (020 7609 1800)