I have no mouth yet I must scream...

The human animal has been trapped for a long time. Whether this prison is the ruins of the modernist optimism, or the light shed by that big bomb that was dropped on Hiroshima revealed the exact dimensions of the cell is unclear: either way, ever since Beckett announced the condition of existential angst in Waiting for Godot, the theatre has been reminding humanity of its essential despair. Humans know that they are going to die, and the bit after birth is just a protracted slot in eternity's waiting room.

Future Ruins noticed that the illustrations on the walls of the prison look exactly like a frozen middle-class dinner party. Exterminating Angel - an Improvisation adapts a classic Maurice Maeterlink number about a bunch of blind people lost in the forest and Luis Bunuel's fascination with The Discreet Charm of the Bourgeoisie, and translates them into the polite language of the chattering classes. Meanwhile, Greyscale and Stellar Quines are touring the debut of Sylvia Dow, A Beginning, A Middle and An End. This time, the trap is being sprung on a couple, their children and a forest of advocado trees, which might represent a glimmer of hope.

Dow is bolder in naming Godot at the start of the action: her three characters prologue their lives in a limbo state, before building and deconstructing a life together, then sliding back into the limbo. Director Selma Dimitrijevic is fond of metaphysical theatre - her own script, A Prayer, is the most convincing description of faith written by an avowed atheist - and leaving the context of the character's vague allows an austere, but compassionate, meditation on the doubts and hopes of being alive.

Although Jack McNamara devised and directed Exterminating Angel, the cast of five are free to improvise around similar themes: that it ends in an updating of Plato's cave parable (the one person who braves leaving is tied up and silenced) reveals a serious, brutal intent. The palpable sense of threat that pervades the hour suggests, as in A Beginning, that society is breaking down. Unwilling to brave the outside world, they content themselves with small talk, until the paranoia inevitably cracks open a few nasty home truths.

A Beginning and Exterminating Angel share a fascination with the consequences of threat on individuals trying to hide their fears. The consequences are very difficult: for Dow, death appears as a reunion, and the references to Biblical stories and nature's indefatigable nurturing lend her impatient couple both m eaning and emotional depth. The aspiring dinner party guests over in Angel, however, can only reject any potential escape. Their loathing of each other, hidden behind games and a dishonest respect for emotional honesty, leaves them trapped in a hell made worse by their attempts to ameliorate their situation.

Of course, the themes of waiting and capture by circumstances are familiar: Beckett made a career from it, and Sartre's Huis Clos has the "hell is other people" bases covered. Dow does introduce a note of spiritual acceptance that softens the blow - the finale is a rather lovely folk song about the magic of advocado trees, and Future Ruins have a nastier after-taste: yet these themes are likely to remain popular. After all, the human animal has been trapped for a long time.