Dreary, foggy, fishy-smelling Port Enshus is host to the 305th Annual Aquatic Life Acquisition Simplification Exposition featuring the infamous inventor, Dr. Nimrod Crowley. Expressly forbidden from concussing any gulpy townspeople, assisting any villainous scientists, blowing anything up - even just a shanty or two - or having any fun whatsoever, lovable, precocious and clinically insane young scientist Agnes Crowley is bored out of her skull.

To alleviate her boredom, she visits the local pub where the fishy dregs regale her with tales of twisted ghosts and deadly monsters lurking about the mysterious Kelpie Wharf. Agnes is eager to investigate the dubious claims, but when she arrives at wharf, instead of kelpies, she and the fishy dregs discover two ships come to port, whose crews have vanished without a trace.

Armed with naught but tremendous precociousness, an arsenal of death rays, stun guns, ear trumpets, and concussion cannons, Agnes and her ubiquitous companion, Vic, a re-animated clockwork cadaver, set out to discover what has become of the missing men. But to uncover the secrets of the disappearance and the enigmatic island that may hold the key to the mystery, they must first face an army of werewolves, bogeymen, revenants, bog monsters, Spring-Heeled Jacks, and other legendary monsters of lore.