JK Rowling has urged audience members to avoid giving away secrets to the stage version of Harry Potter.
'Harry Potter and the Cursed Child' opened for previews in London on Tuesday and picks up the story of the boy wizard, 19 years after the last novel.
The much-loved characters Ron and Hermione also appear, but little else has been revealed of the story and Rowling has asked audiences to not spoil the plot for others.
In a series of tweets using the hashtag #DontBeWormtail - in reference to the scheming character Peter Pettigrew - she wants fans to #KeepTheSecrets "for each others sake".
Audience members have been issued with #KeepTheSecret badges as a reminder, with the play due to officially open at the Palace Theatre in London on July 30.
Reaction to the opening preview has been widely positive with Rowling describing the reviews "wonderful".
"I really liked the films but after seeing this, I would say, forget the films," fan Callum Fawcett said. "This is fantastic. It's got everything."
"It was utterly remarkable, just incredible," fellow fan Ollie Southgate added. "It's a whole different version of everything that everyone loves about the books. The visual effects they've got is like nothing I've ever seen."