At the end of Tarzan and the Lost City of Opar, La is seen carrying around a long, golden staff that helps harness her dark, magical powers. It has a handle resembling the shape of a leopard's head and in its mouth is a large red gem. With this staff, La can summon rain, vaporize her Leopard Men, and when possessing Jane, switch into her own clothes and repair and rebuild Opar.
While out in the jungle, Professor Porter is captured by anthropomorphic Leopard Men. They bring him back to the lost city of Opar, a hidden ancient city high up in the mountains. There, it is revealed that a figure by the name of La had sent them to capture her a mate. Disappointed, she commands her people to sacrifice the Professor. Before he can be sliced in half by a sun-powered laser, Tarzan and Jane show up to free him. La watches Tarzan fighting her men off from a balcony above and is smitten by the wild man. She then offers them a tour of Opar. During the tour, she tries various attempts to flirt with Tarzan, only to have Jane get in the way. The queen then offers them to spend the night in Opar while she plots of a way to kill Jane. The next day she talks to Jane, making her feel as though she is a burden to Tarzan. La then offers both her and Tarzan an outing in the jungle, knowing only Tarzan could make it and not Jane. Jane tells Tarzan to go ahead while she mopes back to Opar, unknowingly followed by the Leopard Men. Meanwhile, La leads Tarzan up to a waterfall and tries to have a romantic moment with him when the Leopard Men toss Jane over the side of a waterfall back at Opar. Tarzan rushes off to save her, but is too late.
As La tries to act innocent, Tarzan discovers the Leopard Men pushed Jane over the side and attacks. He is pinned down, and La tries to convince Tarzan to join her. He refuses and is then strapped to the sacrifice table himself. La offers him a choice of staying with her or death. A faithful Tarzan chooses death, and the sun laser begins to make its way to cut Tarzan in two. Suddenly, a fire bursts out and La goes to investigate. It is then revealed that Jane is alive. La follows her through Opar, determined to finish her off, when Tarzan arrives and distracts La long enough for Jane to grab La's staff and use it to get herself and her family out of Opar.
As Opar burns down and Tarzan rides off with Jane and the family, La summons rain with her staff and swears revenge against Tarzan and Jane.
Later, La would be overthrown by her Leopard Men, including Kaj, and her staff was taken from her. The Leopard Men then break into Tarzan and Jane's treehouse, kidnapping Jane. While Tarzan pursues them, he runs into a powerless La who is cornered by a rogue leopard. He saves her and the two reach a mutual truce in order to free Jane. They succeed and La takes back possession of her staff from the entranced Jane. When Tarzan leaves with Jane she begins to punish all the Leopard Men who rebelled against her, most of all Kaj. Later, Tarzan discovers that Jane was taken so the Leopard Men could make her their new queen and free them from La's oppression. Sneaking into Opar, Jane and Tarzan manage to take the staff away from La, so that Jane can perform the ritual to restore the Leopard Men to their original leopard forms. Jane breaks the staff and La is turned into dust, with Opar falling into ruins with it. But before she dies, La places a curse on Jane.
As Jane, Tarzan, the Leopard Men and the rest of their friends leave, it is revealed that the staff has fixed itself and La's sinister laugh can be heard echoing into the ruins of Opar.
While setting up a croquet tournament for her father, Jane discovers a fallen okapi and tries to nurture it to health. Unknowingly, the animal contains the wandering spirit of Queen La. Seeing Jane, La takes control of her body and tries to revive the city of Opar with it. Yet Jane's body is too weak and frail to climb the bluff in order to reach Opar. Realizing she needs help, La first tries to convince Tarzan to take her on a romantic outing. When this fails, she seduces Dumont into helping her. Unknown to La, Tarzan is worried for Jane and follows her. La takes care of this by slipping on a rock, dislodging boulders which fall on Tarzan as he climbs after Jane. Believing she no longer has to worry about Tarzan, she forces Dumont to dig up the first half of her staff (the leopard head handle) and when she finds the other one Jane's hair is unbundled and her clothes change into La's sarong and bikini top as well as all her jewelry. Her voice also changes from Jane's normal high pitched voice to La's low, soothing voice. Dumont tries to flee, now terrified of Jane in her new appearance, but La (tired of Dumont already) uses her staff to conjure him into a gibbon. She then uses her staff to resurrect the Lost City of Opar to all of its proud glory.
Little does La know that Tarzan survived the boulders, with the assistance of local Waziri mystic elder named Usula, who explains to Tarzan that La possessed Jane. The two climb up the mountain only to discover Opar is back to it's glorious state. The two sneak into the palace where Usula tries to kill La with an arrow, but Tarzan messes up his shot, believing he can free Jane from La. This fails, however, and La summons for Statue Warriors to kill Tarzan. The warriors follow him, but eventually lose him. Usula then tries to explain to Tarzan that Jane is gone and why she must be killed, but Tarzan offers himself to die instead.
He finds La and kicks her staff out of her hand, then jumps off a balcony with La over her shoulders. Wishing to avoid her demise, she exits Jane and possesses Tarzan. Using his body, he stops their descent towards the ground and plans to kill Jane, calling it a "tragic twist." Jane escapes, only to be cornered in the throne room. Just as it seems she is doomed, the Statue Warriors arrive and try to kill Tarzan, now knowing he is possessed by La. Wanting to live, she transfers her spirit into a rat as Jane and Tarzan defeat the statue. When La tries to flee, Usula snatches her up in a brown sack. The staff is currently in Usula's possession, who uses it as a croquet mallet.