Guitarist John Petrucci tells Rolling Stone: "I wanted this not only to be a concept album, but a full show. We needed the storyline, a plot, places, characters, maps - you name it.

"I'm a huge fan of the sci-fi and fantasy genres, so I had a pretty good idea of where I wanted to go. But it was a matter of really diving into it and working on it, revising and revising again, and working on it every day until I had something solid."