"The Human Equation" is, at this point, my favorite album of all time. It beats out Pink Floyd, Metallica, and anybody else you can think of. Really, though, that's my opinion. Still, I reccommend that any fan of metal, progressive rock/metal, or just rock in general, give this album a listen. Also, if you're a fan of good literature, at LEAST go and read the lyrics!
The story is tied in vaguely, at the very end, to "Universal Migrator". Basically, the main character, sung by Dream Theater's James Labrie, catches his wife (Marcela Bovio - Elfonia) with his best friend (Arjen Lucassen, the composer of the Ayreon project). He leaves without speaking to them and crashes his car into a tree in broad daylight with no other cars around. He then goes comatose, and is trapped inside of his head, facing up to his emotions, his past, and his inner demons until the last song. Meanwhile, his wife and best friend sit at his bedside and seek to break through the blackness to help him recover. He also gets a visit from his father, which is very...interesting, to say the least.
Overall, the story is a wonderful summation of the human mind and experience. It paints a portrait of the intricate relations and emotions that we experience on a daily basis.
It also features an all-star cast, including Opeth's Mikael Akerfeldt (Fear), Devin Townsend (Rage; Strapping Young Lad), Irene Jansen (Passion; ex-Karma), Eric Clayton (Reason; Saviour Machine), and Devon Graves (Agony; Dead Soul Tribe, ex -Psychotic Waltz), aside from the aforementioned trio that play the three main characters. Also, Shadow Gallery's Mike Baker plays the Father, though he only gets the one song.
Again, I can't praise this album enough. I, personally, suggest that anybody try it once. You can find "Loser", "Come Back to Me", and "Love" on youtube, if not all of them. Just search for Ayreon - The Human Equation. Sample it.