Stephen Sondheim is both composer and lyricist of this musical version based on Christopher Bond's adaptation but a lot of the pleasure of this play lies very much in the words.

Where a lot of musicals take the easy way out by choosing trite rhyming schemes, Sondheim's lyrics are clever and multifaceted so it is no surprise to learn that Sondheim once worked as a cryptic-crossword composer.

The story of Sweeney Todd is based on the story of Todd, a murderous barber in 19thcentury London.

Briefly, without giving too much away (this is a thriller after all), Sweeney Todd is a barber sentenced to life imprisonment in the penal colonies of Austrialia.

He escapes and returns 15 years later seeking the wife and baby he left behind. When he finds his wife is presumed dead and his daughter is in the care of the predatory Judge Turpin, he resolves to get revenge.

Returning to his old barber's premises he meets up with the proprietor Nellie Lovett, who becomes his accomplice, turning his murder victims into delicious pies.

Todd's character is fairly simplistic and David Shannon does well not to overplay the role.

Shannon's voice is strong and deep and perfect for the part of a shadowy murderer and, despite his character's indiscriminate killing, he manages to instill Todd with some humanity.

Anita Reeves, in the part of Mrs Lovett, runs away with the show; the audience loves her, she has impeccable comic timing and gives a great performance, even adding a touch of pantomime with some ad-libbing. When she drops a bonbon which rolls off the edge of the stage into the audience, she says, "You have it, " to a member of the audience, much to the crowd's delight.

Camille O'Sullivan appears here for the first time at the Gate, almost unrecognisable as the beggar woman who has lost her mind. Crazy women are always difficult to play . . . I've yet to see an Ophelia I didn't want to throttle . . . and O'Sullivan errs a little on the side of too much screeching and tearing at her hair. Mark O'Regan deserves a mention too for his fraudster Italian Mr Pirelli. Rick Fisher's lighting is a revelation, offering clarity whilst maintaining an air of shadowy mystery . . . no mean feat I'm sure.

As expected from a play about a barber who uses his blade for killing, there is a lot of cruelty in the play. Knives are sharpened, throats are cut, birds are crushed to death . . . although director Selina Cartmell opts not to use blood for the gruesome killings but a burst of talcum powder and a removal of the characters' wigs to signify their passing.

No musical would be worthy of the name without a love story and that part is fulfilled by Johanna (sweetly played by Lisa Lambe) and Anthony. But what is so enjoyable about Sweeney Todd and Sondheim in general are the many twisted layers he gives to his characters and there are plenty of unrequited love stories beneath the main one.

The play as a whole is wellmanaged by director Selina Cartmell and there are some scenes that work very well, especially the montage showing Sweeney Todd wearily going through his killings while Johanna is locked away in the asylum.

There are also parts, although few, where things nearly fall apart. Notably, the scene where Anthony asks Johanna to elope with him, while the judge is simultaneously planning to marry her.

The various vocal parts get lost in the sheer complexity of the scene and the words become muddy. None of this is helped by the fact that it simply goes on too long.

These patchy moments aside, Sweeney Todd is essentially a hugely entertaining musical and very enjoyable and, thankfully, the Gate has made a big production of it with a live orchestra and a fantastic set.