The little people help a giant man named Kamber who has been shot by police, but he refuses medical help and has the humans contact a woman named Dr. North instead. Once North arrives, it is revealed she and Kamber are part of a terrorist plot to blow up half-a-million people. When she learns that the Earthlings have overheard the plan, she tries to kill them, but the humans manage to escape, with Fitzhugh injuring his leg. Betty and Valerie stay with Fitzhugh, while the others try to figure out a clue left behind by Kamber that could lead to the location of the bombs. However, Inspector Kobick captures Betty and Fitzhugh, and does not buy their story of the terror plot, leaving Steve and the others to foil the plan themselves.