Christopher Isherwood (Harry Melling) sits in a bedsit waiting for something to happen so he can, like the dead, dumb eye of a camera, record it - and in the Berlin of the early 30s, he doesn't have to wait very long.
While the jackboot has already started to march in the street below, Chris'oh-so-polite Oxbridgeness attracts a cavalcade of Weimar's finest to sit, talk, drink, and screw in miserable bedsit lit up by personalities of its habitues. Landlady, Fraulein Schneider (Joanne Howarth), takes to him like the son she never had; man on the make, Fritz Wendel (Freddie Capper) seeks out his advice and matchmaking skills with Jewish department store heiress and Chris' English language pupil, Natalya,(Sophie Dickson) and bored, rich American Clive (Oliver Rix) is just looking for the next distraction.
And few people, ever, anywhere, have been more distracting than Miss Sally Bowles (Rebecca Humphries). A child-woman, devoid of the superego's restraints on the id's drives, she is a force of nature. In sequined hot-pants with a gin in one hand and a fag in the other, she sweeps Christopher along with tales of debauched nights with rich old men, future adventures in South America and India and a roiling energy that fills every space in her life and Christopher's.
For all the gentle charisma Melling invests in his Isherwood and the strong performances of the other five players, I am a Camera (and Cabaret, the musical and film it spawned) is all about Sally. Rebecca Humphries blitzes the role, flashing scheming eyes below a shock of red hair, preening green nails on hands that betray how many glasses, cigarettes and, well, other things, they have held and an attention span that would shame a two-year-old on Red Bull. But it is in Sally's more pensive moments - advising Natalya, accepting the inevitable consequence of her chaotic lovelife, fearing her mother - that Ms Humphries' skills come through. We see the woman behind the caricature (legend these days) and we see the empty centre of her hurricane personality.
In The Vaults at Southwark Theatre (until 22 September), John Van Druten's sixty-year old play still sparkles with wit, but doesn't lose the bite of its context, especially in underlining the banality of the Nazis' appeal to the ordinary German. Anthony Lau has directed a classic, but has ensued that it is as relevant today as ever – and just as much fun.