There's some benign name-dropping going on here. I suspect that, had he not recently adapted All About My Mother for the Old Vic, Samuel Adamson wouldn't have seen his one-woman play produced in the commercial West End, albeit in this tiny studio space. For although Some Kind of Bliss passes 75 minutes pleasantly enough, its inconsequentiality is hard to escape.

I'd normally go to considerable lengths to avoid any piece with this kind of oppressively quirky opening. "Today - after I'd had the electric sex, got clobbered, killed the dog and parked the hijacked ice-cream van - I found the pop legend's house in Greenwich," recounts Rachel (Lucy Briers). This exhausting pile-up of images is, fortunately, not entirely representative, as Adamson takes Rachel, and therefore us, through a thirtysomething's intriguing, low-grade "Is this it?" life crisis.

In Southwark Fair, a previous play for the National, Adamson proved himself something of a master of the genre of contemporary Thames-side whimsy. There's much more of that here as Rachel, a Daily Mail journalist, suddenly decides to walk the Thames Path from London Bridge to Greenwich, where she is to interview Lulu.

Adamson captures nicely the catalyst of fresh surroundings, as Rachel uses this unscheduled time for reflection. She is, it appears, constantly torn, between trying to be cool enough to live up to the memory of the late uncle she adored unrequitedly, and sufficiently intellectual to satisfy her academic father and the ex-boyfriend who matters far more than her husband.

Adamson has set himself a tricky task, as this sort of piece runs on narrow tracks and can derail exceedingly easily. Something needs to happen to sustain narrative momentum, but it must happen organically. Increasingly, the lurches into the bizarre don't feel well enough earned and, somewhere between the sex and the clobbering, this tips from plausibility into the sort of day that only occurs in films and plays.

Luckily, Briers is an engaging performer who, in Toby Frow's sparky production, makes Rachel a sprightly, wry commentator on her own life. She has great fun with the many sharp lines - a hot dog man "sells salmonella" - and works hard to differentiate the flashbacks, cleverly inserted by Adamson to break linear monotony, from the present-time river walk. Some kind of bliss, for sure, but not theatrical nirvana.

• Until 15 December. Information: 0870 060 6632. www.the ambassadors. com/trafalgar studios.