The Great and Secret Show is a novel by British (although he now lives in the USA) author Clive Barker. It was released in 1989 and it is the first "Book of the Art" in a trilogy, but it also can be read on its own.
Clive Barker has said in interviews that this novel has been the one that has been the hardest to write for him.
The second part of the "Art" trilogy, Everville, was released in 1994.