Sweeney is back after three decades, according to the genius behind the hit musical.
Lovett Never Dies will pick up where the 1979 original left off. While Sweeney fans assume the title character and his pie-making landlady, Mrs Lovett, died at the end of the first show, the follow-up reveals the pair were saved by a kindly cockney bootblack.
Sweeney disappears, but 10 years later, Mrs Lovett receives a letter from the mysterious "Mr T," a flamboyant New York barber-surgeon, inviting her to America to make pies.
Meanwhile, in the solitude of his vast barbering empire, Mr T will pine wistfully for Mrs Lovett's savoury goods, a yearning expressed in the show-stopping number Till I Eat Her Pie Once More.
"Die-hard purists will probably object to the new concept," said Sondheim, "especially the revelation that Sweeney and Lovett shared a night of passion among the pastries as they bled to what we all thought were their inevitable deaths."
Other songs in the musical will include Beneath a Spoonless Pie and Look with Your Tart.
Andrew Lloyd Webber will produce.
