In this franticly paced tale, Gorilla Grodd attacks the League, while Captain Marvel is lured into the hands of the villains. It's the World's Mightiest Mortal vs. The Man of Steel--and only one can win!
Hal Jordan shares his suspicions with the League at the Fortress. Hal presumes that Brainiac never wanted him dead, aiming only to keep the ring off Earth. Examining Captain Cold, Hal discovers miniaturized mind-control worms in his brain. Captain Marvel remarks that the villains were never loyal to each other, so the worms may be the only thing keeping them together.
Doc Magnus discovers that although the worms can penetrate armor and clothing, they can be repelled by Green Lantern's forcefield. Magnus proposes building special armor, scavenging his Metal Men for raw materials and their responsometers. Ray Palmer starts building non-sentient suits with Thanagarian and Atlantean materials for the leaguers.
The League tracks Gorilla Grodd to an African stronghold; Grodd is bearing a Qwardian ring. Black Adam, Mary Marvel and Captain Marvel, Jr. fight Captain Marvel. Using Billy's feelings for his sister and his protegé against him, Adam manages to bring him under Brainiac's control.
Bruce Wayne brings Clark Kent to Leslie Thompkins' foster care home. There he examines a child "healed" by Brainac, discovering that Brainiac has gained the ability to reshape humans into organic machinery.
Luthor inspects an army of Brainiac's lookalikes, built by the Toyman, and plants a hidden bug into one of them.
The battle with Gorilla Grodd ends in a standstill, with Sinestro coming to aid of his wounded teammate. Metamorpho manages to steal Grodd's Power Ring before his escape.
A mind-controlled Captain Marvel tries to breach the fortress, but is stopped by Superman and Green Lantern. The latter frees him from Brainiac's worms. They take off for Arkham, where they find Doctor Sivana, in a catatonic state induced by the worms. After freeing him, they discover that the worms are in fact Sivana's doing, reshaped and miniaturized by Brainac.
As the heroes set off for their battle, clad in armor, Luthor frees Captain Cold.