THE sign of a good comedy, says Hull Truck playwright John Godber, is when the audience is rocking with laughter. In contrast, the sign of a good thriller is how quiet the audience is.

By that token, the sign of a bad comedy is how quiet the audience is; the sign of a bad thriller is when the audience is rocking with laughter.

What happens, however, when a playwright has a natural inclination towards comedy, no matter the situation, and elects to write a darkly comic thriller of murder and mystery, ghosts, pigs' heads and guilt? Ideally, the comedy should serve as a relief, a release, from the mounting tension. The problem comes when there is insufficient tension for the humour to rub up against, and Screaming Blue Murder suffers from exactly that defect.

"Writing humour is like a disease," admits Godber, whose first foray into the murky waters of the English psychological thriller ends up as neither spooky nor highly humorous. Instead he has succeeded only in blurring his distinction between good thrillers and comedies?

Psychological thrillers, from Agatha Christie to Alan Ayckbourn's Haunting Julia, can straddle that divide, and indeed Haunting Julia inspired Godber to write Screaming Blue Murder. A second Ayckbourn work, House & Garden - in which the same cast performs two plays simultaneously in different auditoria - led him to write sister plays in Screaming Blue Murder and Black Tie And Tales. Both are staged by the same cast, and the interlinking events take place on the same night in different rooms at Bagley Hall, a haunted hotel run with the erratic, psychotic skills of the Fawlty Towers school of management.

By way of contrast with House & Garden, the Godber brace is performed on separate nights, and in York at separate theatres (Black Tie And Tales will form part of the Theatre Royal summer season).

Both plays are studies of guilt, in the case of Screaming Blue Murder the guilt felt by the nervy Nick (Robert Angell) as he plays away from home with Gill (Fiona Wass) for a dirty weekend at a Murder Mystery convention. They are not the only thing that will go bump in the night, however.

Both hear voices through the wall although neither can hear what the other is hearing. With her gift for seeing into the future, she is foretelling her own exit stage left; he is convinced his wife Annie is next door. Then there are the constantly intrusive hotel staff, Godber's conduits for humour and mystery, in the shape of Eastern European house maid Maria (Amy Thompson), irascible porter Ronnie (Dicken Ashworth) and camp mine host Colin (Ashworth again).

Nothing is as it seems: even the play, which has initial promise, but is in fact a folly.

The pig's head turns out to be a pig's ear.

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Updated: 10:26 Tuesday, February 17, 2004