Book 4 in the hilarious series.
Though Hank was pretty much immobile by the end of book 3, somehow another mutant was able to give him a new body.

… Hank’s greatest facet as the series’s hero is how despite the changes that occur all around him, the major shifts in the dynamic of his setting, he remains immovably the same.
Hank is Hank, and will always be Hank.
His character is the (sometimes literally) immovable object around which every major event in the series finds itself orbiting. …
These books might not ever be featured in any overly self-important critic’s list of must-reads or forced on future students of literature as cultural classics, but they’ve certainly earned a place in my personal hall of fame as one of the most thoroughly entertaining reads I’ve ever had the pleasure of burning away free time with. …