The Mystery of The MOCKER! An immortal Guardian has died on Oa amidst mocking laughter. The present Green Lanterns quickly exit the building and spot an alien craft. The craft activates Vapor Drones (seemingly sentient cloud fighters) which engage the Green Lanterns. Deducing the clouds are taking orders from the ship, Hal Jordan smashes through the hull but is immediately gassed and captured.
On Earth, Green Arrow and Black Canary watch over an injured and sleeping Katma Tui. Carol returns with a doctor. As they take Katma to his car, the group is attacked by Junior Musto, son of terrorist Musta Musto, who are looking to kidnap Carol Ferris. The heroes capture them but, in the confusion, Katma apparently wanders off.
Back on Oa, the aliens take the captured Hal Jordan to a mothership planning to connect him to an Analyzerum machine to discover how the Green Lanterns are able to resist the Vapor Drones and how they discovered the spy Guardian (the one who died). Hal attacks, destroying the machine while admitting he faked unconsciousness in order to learn the aliens' intentions.
