• General view of at Universal Orlando on January 31, 2015 in Orlando, Florida.

General view of at Universal Orlando on January 31, 2015 in Orlando, Florida. (Photo : Getty Images/Aaron Davidson)

Preview performance of the upcoming London play, "Harry Potter and the Cursed Child," has left J.K. Rowling in worry. The novelist and screenwriter is concerned about people who cannot stop themselves from talking about the plot.

The author of the Harry Potter series left a serious message for the fans through a YouTube video, requesting them to zip their mouths and abide by their decision not to spill the beans. She praised her fans saying that she appreciates how people kept secrets so that they don't spoil the surprise for other readers.

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"So I'm asking you one more time to keep secrets and let audiences enjoy 'Cursed Child"' with all the surprises that we've built into the story," she said, according to E! Online. "Potter fans have always had each other's backs."

"Harry Potter and the Cursed Child," is slated to debut at the London Palace Theater. The stage play narrates the life story of the leading character in the series, Harry Potter. He is depicted as an "overworked" employee in the Ministry of Magic. It also includes his son Albus Severus Potter.

The play was sparked by a controversy several weeks before its debut. The show was being questioned for casting the British actress Noma Dumezweni as Hermione Granger. In the "Harry Potter" film series, the character of Granger was played by actress Emma Watson.

People and fans criticized Dumezweni's darker complexion. However, Rowling hit back at them saying that she never described the complexion of the character or her race at any point of time.

The play - which is set to begin preview performance in London on July 7 - will be inaccessible to all but a selected number of fans, according to TIME. A book of the script is yet to be released. Meanwhile, those who wish to see the play will have to go to London and purchase a ticket for the show. The printed version of the play is expected to release by the end of the month.

This is not the first time that a piece of art has been subjected to spoilers. People ardently wait to find anything that they can about their favorite work of art, everything from "Game of Thrones" to the "Mad Men."

The following video talks about Rowling's plea to her fans: