The Justice League of America are summoned to a secret S.T.A.R. Labs facility. The facility has been left in ruins, likely to conceal the theft of a mutagenic compound. At great risk to himself, the Elongated Man confirms the theft of the compound. Zatanna attempting to pull psychic impressions off a compound canister, suddenly screams, and collapses. Zatanna awakens, aboard the satellite headquarters of the Justice League of America. The Elongated Man tells Zatanna that the Green Lantern was able to track the stolen compound. Zatanna reveals that she has been enchanted by a spell of forgetfulness. She has no idea when, or why, she started wearing her new costume.
The Justice League of America travel to the Miami Radiological Research Center, in Florida. An sudden tidal wave forms along the shore. The Green Lantern dissipates the wave, only to be attacked by a giant squid, protected by a yellow force field. Superman races into the Miami Radiological Research Center. Wonder Woman binds the squid in her Lasso of Truth. A figure, moving so fast as to be invisible to the naked eye, bowls the Green Arrow and Wonder Woman over. Superman emerges from the center, staggered by some kind of psychic attack. The Elongated Man, the Red Tornado, and Zatanna begin their investigation into Zatanna's mystery, at the Fox Theater.
They find little trace of her father, Zatara. Zatanna sees an image of her family in an old photograph. Neither the Elongated Man, nor the Red Tornado, however, see Zatanna's mother in the picture. Zatanna transports them all to her family home. The Justice League of America journey to Deepsea Probe "Proteus", an underwater facility off the coast of Louisiana. Superman finds the facility's scientists locked in cages. The Justice League of America is attacked, and subdued, by the Shark. The Red Tornado reports on a powerful magnetic anomaly within Zatanna's home. When the Elongated Man attempts to enter the house, it literally comes to life. Zatanna freezes in the face of such horror.
The Red Tornado saves Zatanna from harm, suffering the house's attack in her stead. Seeing the Elongated Man in mortal danger, Zatanna exorcises the Banshee animating her home. Dissipating the banshee reveals a partially formed dimensional portal, emanating from the house. The Shark reveals that, out of loneliness, the Shark stole the mutagenic compound to create predator companions. The Shark unleashes the Princes of Prey. The Justice League of America break their bonds and confront the Princes of Prey.
The Green Arrow fires a battering ram arrow that hurls the Scorpion back into the mutagenic chamber. Wonder Woman punches the Raptor back into the mutagenic chamber. The Justice League of America force the Shark, and the Rat, back into the mutagenic chamber. Superman seals the mutagenic chamber with his heat vision. The Green Arrow devolves the Princes of Prey, and the Shark, into amoebas. Zatanna dissipates the dimensional portal, revealing her father, Zatara.