After Tova Sullivan's husband died, she began working the night cleaner shift at the Sowell Bay Aquarium. Ever since her eighteen-year-old son, Erik, mysteriously vanished on a boat over thirty years ago keeping busy has helped her cope. One night she meets Marcellus, a giant Pacific octopus living at the aquarium who sees everything, but wouldn't dream of lifting one of his eight arms for his human captors – until he forms a remarkable friendship with Tova.

Ever the detective, Marcellus deduces what happened the night Tova's son disappeared. And now Marcellus must use every trick his old body can muster to unearth the truth for her before it's too late...