This is one of the more twisted of King's books that I've read. Thad Beaumont had an operation when he was a kid. In the course of the operation, the surgeon discovered remnants of a partially absorbed twin inside Thad's skull--a twin that was removed, before the internal pressure inside his head could kill him.
Years later, Thad is a successful writer. Except his most profitable series is written under the name George Stark, instead of his own. George is a mighty crafty, awfully psychotic fellow.
And he's come to get revenge on Thad for killing him.
This book is typically bloody and twisted, perhaps a little more than the usual fare, for King. It's a great book, and I can't say that I've read anything like it before. If you like novels with horror, murder, and mayhem, this is a book for you!