Batman and Harley Quinn

Batman and Nightwing realize Ivy and Floronic Man have formed an alliance and stolen S.T.A.R. Labs data on the Bio-Restorative Project and Swamp Thing. They decide to locate Harley Quinn to learn where the duo is hiding.

At AR.G.U.S. Headquarters, Batman asks Sarge Steel about the kidnapped scientist Dr. Harold Goldblum. Sarge confirms there are no viable leads at the moment.

Nightwing locates Harley Quinn working as a waitress at the Superbabes restaurant. He presses for information about Ivy and Floronic Man, but she insists she wants a normal life and questions why she is still in a skimpy costume for minimum wage.

The two clash as Nightwing presses her further, and Harley knocks him out with a weak dose of Joker Gas. He slumps unconscious while she asserts she won't return to crime on his terms.

Sarge shows Batman the home of Dr. Harold Goldblum, where he was kidnapped. Batman finds evidence that Floronic Man had been there.

Nightwing wakes to find himself tied to a bed. Harley reveals rejection letters and explains her criminal past has kept her from rejoining the psychiatric field. The moment ends with the two sharing a kiss and eventually sleeping together.

Ivy keeps Goldblum under her control by kissing him every six hours, using pheromones to influence his actions. The plan is framed around enabling their virus-based transformation.

Batman concludes the criminals plan to use Goldblum to replicate Swamp Thing's process via a virus that would turn everyone into plant hybrids. After Nightwing encounters Harley again, she decides to help them stop Ivy and Floronic Man.

Harley guides them to a henchmen hangout to locate Ivy by getting information from her old minions, Shrubby, after performing Blondie's 'Hanging on the Telephone'. They must fight their way through henchmen to reach Ivy.

They fight their way through the hangout and escape, then hasten toward Blüdhaven where Ivy is arriving with Woodrue. The mission shifts to intercept Ivy before her plan unfolds.

In Blüdhaven, Woodrue fatally wounds Goldblum to keep him quiet, and their lab catches fire. The dying Goldblum reveals that Ivy and Woodrue are heading to Wainwright Swamp in Louisiana for the right chemicals.

Batman, Nightwing, and Harley pursue Ivy and Floronic Man to Wainwright Swamp. Ivy is swayed by Harley's plea and their relationship, while Swamp Thing warns Woodrue but will not intervene in the confrontation.

Harley points out that Woodrue is a plant, turning the plan to their advantage. With Swamp Thing's non-interference, Batman sets Woodrue on fire to prevent the virus from spreading.

In a post-credits scene, Harleen Quinzel launches a reality television game show called 'Ask Dr. Quinzel' where contestants run an elaborate obstacle course to win a year of professional therapy.