Usually, people sing on the stage when mere words are no longer enough. Breaking every rule in the musical theatre book, London Road makes everyday speech remarkable by putting mere words in relief, finding rich patterns in the verbal wallpaper.
And this makes for a still-riveting evening of theatre in Rufus Norris's award-winning production (including a Whatsonstage.com award for best ensemble performance), which has moved effortlessly, seamlessly, from the Cottesloe, where it opened last April, onto the wider, deeper Olivier stage as part of the ongoing Travelex £12 season.
This is a portrait of a Suffolk community in a state of shock and awe at the murder of five Ipswich prostitutes in 2006. And it's almost impossible for one to separate the contributions of Norris, the actors, the designer Katrina Lindsay, the lighting designer James Farncombe and musical director David Shrubsole.
The words of the community were recorded and edited by Alecky Blythe during the trial of the murderer, and then set by Adam Cork - all "ums," "ers" and other conversational tics and curlicues included - to music of a marvellous but modest beauty, pulsing with what I can only describe as a deep moral curiosity and subtle saltiness.
And 52 other parts - policemen, journalists, lawyers, neighbours - are all played fleetingly by the other characters including Clare Burt as a part-time carer, Hal Fowler as her husband and Michael Shaeffer as a prize-winning gardener. The normality of these people is celebrated, as well as their part in reclaiming a sense of civic pride.
Last year, the show was slightly affected by the protests of one of the victims' mothers; but when three of the company stand stock still as "working girls" in a haze of drugs, the moment is one of dignity and compassion, no hint of sensationalism or exploitation.
The killer Steve Wright, dubbed "the Suffolk strangler" and now serving a life sentence, had rented a room for ten weeks on London Road in the red light district of Ipswich near the old football ground, an area now transformed by its residents and their tea parties and flower baskets of begonias, petunias, fuchsias and, as the cast sing, "um, impatiens and things."
People talk of the curative powers of music, and in London Road the cast literally sing their way to living with the past and facing the future. Traditionally, musical theatre is about aspiration, triumphalism, falling in love and changing the world.
This extraordinary piece concentrates on the ground level business of patching and mending and surviving and re-defines the priorities in our everyday lives in the aftermath of one almighty blip, the bane and banality of evil. Above all, it proves that we're all in this together.