This is a rhymed verse novel concerning a humpback whale lost in the Sacramento River delta, who meets land animals that relate tales of terror from a single species. A raccoon reveals how it came to wear a furtive mask. A heron speaks of poisoned waterways. A frog describes a skin-raising scene in a land of giants. A dog named Ralf uses black humor to recount hair-raising experiments done on animals. Then a beaver builds a dam that blocks Humphrey's forward progress. The first people to discover Humphrey are two big game hunters and a 12-year-old girl. Their meeting triggers a contest between advocates for and against the "homicidal humpback." The battle is joined by the Navy and the Coast Guard on one side, and hundreds of rescuers on the other. An Inuit bowhead whale hunter is brought down from Alaska to dispatch Humphrey, while rescuers try to lure him downriver. Then Ralf returns. This morality tale with a Hollywood ending proves the truth of that old saying, the dog is a whale's best friend.