We see the Hulk take on a gamma-powered bomb, which should have destroyed him; instead, it sends him on a rampage into the heart of Las Vegas, which is stopped only by the Fantastic Four's Thing. Seeing how dangerous the Hulk can be (as if it wasn't already obvious??), Nick Fury comes into play and tricks the Hulk into going into space. The Hulk soon learns that he has been lied to, and eventually, he's shipped off further into space.

While this is the prelude to Planet Hulk, it's not really necessary to read this trade to enjoy Planet Hulk. In fact, this trade has very little to do with explaining how Planet Hulk comes to be anyway. Planet Hulk does a sufficiently good job of explaining what happened to the Hulk and why, and it's much better written than this trade is. Save your money and jump straight to Planet Hulk. ( )