London’s The Young Vic Theatre has announced an extended run and additional cast members for Tim Crouch’s groundbreaking play “An Oak Tree,” which will now run from May 6-24, marking the production’s 20th anniversary.

“Bridgerton” star Adjoa Andoh, Oscar nominee Jessie Buckley (“The Lost Daughter”), Mark Gatiss (“The League of Gentlemen”), Arthur Darvill (“Broadchurch”), Julie Hesmondhalgh (“Mr Bates vs The Post Office”) and Alex Lawther (“The End of the F***ing World”) have joined the lineup of guest artists who will perform opposite Crouch in this unique theatrical experiment.

They join previously announced performers Sope Dirisu (“Gangs of London”), Michelle Terry (“Tribes”), Luke Thompson (“Bridgerton”), Russell Tovey (“Being Human”) and Indira Varma (“Game of Thrones”). The identities of the guest performers will only be revealed to audiences when they step on stage each night.

Written, performed and co-directed by Crouch, “An Oak Tree” pioneered the concept of theatrical “cold-reading,” where each guest artist performs the play without having seen or read it beforehand, and will only perform it once during the run. Since its 2005 premiere, more than 350 different guest artists have appeared in the play across 19 countries, including Frances McDormand, Geoffrey Rush, Sharon D Clarke, Alanis Morissette, Sophie Okonedo and Peter Dinklage.

The play tells the story of a father who loses his daughter in a car accident. The driver who killed her is a stage hypnotist, and the two men meet when the father volunteers for the hypnotist’s act.

“Exactly twenty years ago a laboratory was created in a small room above a pub in South London where an experiment took place,” Crouch said. “Actors were invited to try out a new play I’d written called ‘An Oak Tree’ – like trying out a new drug formulation. Each time a different actor who knew nothing about the play they were going to be in – a blind test each time.”

He added: “Twenty years later and that experiment is still ongoing with 374 blind tests to date. 374 actors who have done the play with me. And the laboratory has moved on from London to New York to LA to Russia to South America to Australia to Asia.”

“An Oak Tree” is presented by Francesca Moody Productions, the Olivier Award-winning producers behind “Fleabag” and “Baby Reindeer,” in association with the Young Vic. The production is directed by Crouch, Karl James and Andy Smith, with music by Peter Gill.