WHEN Dutch actor Titus Muizelaar rips up a poster for Sea Urchins (director: Irina Brown of this parish), it's a nice in-joke for the local audience. But when Lineke Rijxman flicks through a copy of Trainspotting nearer to the start of Buff, it's more than just an easy sight-gag. It's a warning that when it comes to grossness, the Dutch can out-Welsh our ain Irvine any day.

Performed in the Tron Theatre bar - dreadful sight-lines, great atmosphere - Gerardjan Rijnders's self-directed play makes out it's about an apoplectic theatre critic (Muizelaar) ranting about a bad night out. It's really about his all but silent wife (Rijxman) and son (Fred Goessens), whose unarticulated despair sends them into a frenzied charade of physical and mental destruction.

The joke (and Buff provokes the riotous laughter of grim disgust) is that the critic is oblivious to the shooting-up, maternal rape, and eventual murder taking place in his living room, even while he mourns the death of drama.

The desperate acts of mother and son - he searching mouth and genitals for a decent blood vessel, she tidying up while her own child ravages her - are presented to comic excess. Earlier in the evening in the theatre proper, something of the same unvoiced anxiety is explored in an utterly different way by the same Toneelgroep Amsterdam company in Harold Pinter's Ashes to Ashes.

Performed on an under-lit Perspex stage with the clinical look of a laboratory experiment, Pinter's 1996 two-hander is a disturbing portrait of a couple whose middle-class veneer masks an uncertain history of private and public terror.

Director Titus Muizelaar makes it all the more unsettling by having the actors (an angular Rijxman, and a boyish Pierre Bokma) play with an economy quite at odds with the horrors they are concealing. Their chief weapon is the non-sequitur; all that gives them away is the smallest detail of body language.

As examples of a company's range, these plays couldn't be further apart. From the enigmatic edginess of the Pinter to the full-on obscenity of Buff, they might not change the face of British theatre, but they'll certainly shake up your evening.