Moleiarty, the fiendish genius marketer and mole from the deep unground, has rallied his fellow race for an attack to take over the surface city of St. Canard. Stealing buildings, he creates a beam to lock the moon in an eternal eclipse - to plunge everything in darkness.

A mutated spider bite causes Darkwing to grow four extra arms! When this causes hims trouble while trying to catch Moliarty, Darkwing adopts a new super-hero identity... Arachno-duck!