After facing off for a second time against the Vampire of Prague, Hellboy - dead and in Hell - comes down with a fatal illness, and seeks the help of an incompetent team of doctors. As he explores the geography of Hell, learning little from a confused pair of map makers, Hellboy gets a glimpse of the new World Tree that he helped to create, stands accused of murder by his own sister and, in a way, brings about the destruction of Pandemonium itself...