An Oak Tree, Pavilion Theatre<br/> Souterrain, Stanmer Park, Brighton Festival

In An Oak Tree, a two-hander by the dramatist and performer Tim Crouch, he is a provincial stage hypnotist whose act has hit the rocks since he killed a girl in a car accident. At times, Crouch also plays the writer and director of the play and the girl's grieving mother. In each performance, a different actor, who has never seen the script, plays the father of the dead girl.

Knowing that the hypnotist has killed his daughter, the father, Andy, comes to the show and steps up when Crouch asks for volunteers. His life has been shattered, but he's looking for answers rather than vengeance.

Crouch makes a devastatingly good hypnotist on the verge of a nervous breakdown - convincingly shallow in his seedy bingo-hall delivery, and agitatedly stumbling over his words. When he recognises Andy - after callously humiliating him - his outer shell crumples to reveal his inner guilt.

The second actor is not expected to improvise. Rather, he follows Crouch's on-stage or whispered directions. There are good comic moments, as when Crouch pulls back from the play to see how his actor is doing. "It's very well written," the actor responds, reading from his script.

Souterrain is a promenade production, by the landscape-theatre company Wild Works, set in Stanmer Park, a charming but declining village a couple of miles out of Brighton. The story is loosely based on the myth of Orpheus' journey to the Underworld in search of his dead wife, Eurydice.

The action begins with a party at sunset to welcome both the audience and the returning soldier Orpheus. Eurydice and her excited friends are dressed as Land Girls, suggesting that it could be 1945, except that Orpheus has been away for seven years. The couple are briefly united, but death is never far away, and Eurydice is blown up by an unexploded grenade from Orpheus' kit bag. Overcome with grief, Orpheus can think only about getting her back, and the audience follows him and his two companions into the twilight Underworld of the village transformed.

Souterrain is a visual and musical feast but also a moving testament to the resilience of a small community under threat.

Festival ends Sunday (01273 709709)