Hal and Pieface are en route to meet up with Carol and Terga for an afternoon double date when Hal suddenly stops the car and tells Pieface to go without him. Hal changes into Green Lantern and flies away. The reason why is such:
Prior to these events a nuclear test had caused a shark to mutate into a highly evolved humanoid shark form. The Shark becoming more and more intelligent begins telepathically seeking prey until it learns of Hal Jordan and his secret identity as the Green Lantern and sends a telepathic message challenging him. This is what had caused Hal to act so rashly so suddenly.

---