Described as a gripping chiller thriller, writer Brian Clemens' Victorian-set The Edge of Darkness is more of a "how, who, where, when and why" than a whodunit - which could leave you wondering whether you were suffering from the same affliction as the central character.

Emma Cranwell's homecoming after a three-year disappearance should have been good cause for celebration. Discovered in a Dublin hospital and suffering from acute amnesia, Emma is brought home only to be confronted by ghosts from the past. Everyday objects cause her great distress. She seems to speak and understand Russian despite no apparent connection to her past. Where has she been, and to what traumas has she been subject so as to cause her this harm? How will the story unfold and who would rather it didn't?

A slow start and lead balloon clues may have you doubting your evening's choice of entertainment. The Edge of Darkness feels rather like a poor relation to Priestley's An Inspector Calls. However, veteran thriller writer Clemens(who was also responsible for the cult series The Avengers) comes through in the second half to deliver multiple twists and an Agatha Christie-esqe (if slightly rushed) ending, played out here to murmurings of "I told you so" from the audience.

Liza Goddard and Tony Scannell (Roach in The Bill) provide the parentage for poor Emma and a jolly fine job of it they do, too. The depth of performance is commendable given the seeming lack of support from the author.

Clare McGlinn (Charlie Ramsden in Coronation Street) takes on the role of Emma. This is undoubtedly a hard part - disturbed amnesiacs not being particularly easy to play - but, nevertheless, McGlinn's delivery is somewhat flat, monotone and under-developed.

Under Howard Ross' direction, the staging is clean and well developed, while Mark Alexander provides the finishing touches with sympathetic lighting (although watch out of some back-stage shadowing which can be a little off-putting).

It may not exactly have you on the edge of your seats, but The Edge of Darkness still warrants a visit, particularly if you brave through to the interval and on into the superior second half.

- Claire Storey (reviewed at New Victoria Theatre, Woking)