"Chemistry" is the eighth episode of the second season of The New Batman Adventures. It originally aired on October 24, 1998.
While attending Veronica Vreeland's (fourth) wedding, Bruce Wayne is the one to catch the garter, and is roped into posing for a photograph with the woman who caught the bouquet, Susan Maguire. Veronica introduces her as a friend of her new husband, Michael. As they dance during the reception, Bruce finds himself taken with Susan - so taken, in fact, that he is distracted during that evening's patrol as Batman, and Robin has to save him from a thug during a routine store robbery.
Bruce takes a leap and calls Susan back. After dating for a few months, Bruce proposes to Susan, and breaks the news to his comrades that he has decided to finally give up being Batman.
A few days later, Bruce and Susan are wed. Everyone is happy for Bruce, except for Dick Grayson, who bets that it will only be a few months before Bruce is back in costume again.
However, the wedding reception at Wayne Manor is interrupted by a phone call from Veronica, hysterically pleading for help and saying there is something "terribly wrong" with her new husband. When her call is cut off with a scream, Bruce's impulse is to charge out of the house to the rescue, but he remembers Susan. She says she understands that he needs to help a friend, and gives her blessing to his going.
At Veronica's mansion, Michael is advancing menacingly on Veronica. She backs into a security vault in her bedroom and activates a grid laser security beams, hot enough to incinerate any thief. Michael smiles and walks straight through the beams, which burn holes in his skin that heal up within seconds. Gasping, Veronica screams again as she is knocked unconscious.
When Bruce arrives, the mansion is ablaze. He manages to enter the vault and rescue the unconscious Veronica just before the house collapses.
At the hospital, Michael runs in, saying he was in a business meeting and just heard the news. Bruce, suspicious, tells him that Veronica will regain consciousness in a few hours, and until then, he's taken the liberty of having her room guarded by police. As Michael leaves the hospital, Bruce orders Robin and Batgirl to tail him.
They follow Michael back to a greenhouse to report to his mistress, Poison Ivy. She scolds him for giving away her scheme too early, but he said it wasn't his fault: he bares his chest, revealing leaves sprouting from it, and says Veronica saw them. Deciding that Michael's disguise is no longer useful, Ivy rips off his outer skin like a dead leaf (causing Robin to retch and almost give away their position), revealing Michael to be a humanoid plant creature. Ivy remarks that they'll have to step up the timetable for their plan, the climax of which involves attacking a yacht cruise for newlyweds that Bruce and Susan are going on.
After Ivy and Michael leave, Robin and Batgirl are attacked by some plants in Ivy's garden, and accidentally find a chemical that disentegrates the plants. They take some of the remaining chemical to synthesize more as a weapon.
On the cruise, Bruce overhears his fellow passengers talking in glowing terms about their new husbands or wives: the passengers are all wealthy industrialists, while their new mates are all "perfect" - so understanding of their spouses' needs or preferences, so accommodating...
Realizing something is wrong, Bruce confronts Susan in their stateroom, and demands to know more about her past, which she has been mysteriously silent about. After a brief quarrel, green liquid starts to leak from Susan's head, and her legs turn into huge vines that lasso Bruce and slam him into the ceiling. Bruce realizes that she is one of Ivy's creations, and she snared him using a concoction of Ivy's famous pheremones. Susan corrects him on one small point: she did use the pheremones to catch his attention, but making him fall in love with her was just a matter of playing the "perfect" woman. Bruce grabs a nearby lamp and electrocutes the vines, allowing him to break free. Escaping the room, he slams the door and jams it shut with a ladder, while Susan yells from inside, "How dare you treat your wife this way!"
On deck, the passengers and crew are panicking, as giant seaweed tendrils are reaching up from the ocean floor and have fouled the propellers, bringing the ship to a dead stop. Ivy and Michael board the boat from a motor launch and Ivy informs the hapless passengers that she has made their perfect mates, who, after their unfortunate deaths at sea, will become the natural heirs to their fortunes. The mates begin robbing their spouses, revealing their plant selves, until the spouses grow angry and fight back.
Announcing that it is time for them to go, Ivy commands the seaweed to tear a hole in the hull, sinking the ship. Robin, Batgirl and Nightwing then show up in the Batwing and use a chemical sprayer to disintegrate the plant-people. They also slip Bruce a Batsuit in a backpack and Bruce sneaks off for a minute to change. An enraged Poison Ivy grapples with Batman. Robin loads the innocent passengers onto Ivy's speedboat, and Batman tells them to leave without him. Eventually, Batman is able to throw Poison Ivy aside just as the yacht's engines overload and explode, breaking the yacht into two parts.
The Batwing, piloted by Batgirl, flies by and dangles a ladder, and Batman grabs hold and is pulled free of the sinking ship, but is unable to grasp Poison Ivy's hand in time. Ivy apparently drowns in the water.
As the Batwing flies away, Batman catches a glimpse of Susan, looking plaintively out of their cabin's porthole before it submerges.
Expressionless, Batman flicks his wedding ring into the ocean.
- In Batman: The Animated Series, "House & Garden," Poison Ivy first revealed her ability to create human replicas from plants, but could only create copies of already existing people; she seems to have overcome this impediment.
- The fact that Zatanna is in attendance at Bruce's wedding indicates that she has somehow learned his true identity, though at their last meeting, in "Zatanna," she knew Batman only as her childhood friend, "John Smith." Zatanna's knowledge of Bruce's secret identity is later confirmed in the Justice League Unlimited episode "This Little Piggy."
- After facing Man-Bat and She-Bat in "On Leather Wings," and "Terror in the Sky," they been both invited to his wedding, after 'Bruce Wayne' decided to invest in them and they became both business partners and friends.