Context: Mystery, Inc. goes their separate ways after becoming bored of mystery solving. Daphne Blake, along with Fred Jones, starts running a successful television series. Velma Dinkley becomes the proprietor of a mystery bookstore, and Scooby-Doo and his owner Shaggy Rogers bounce from job to job. For Daphne's birthday, Fred decides to get the gang back together for a road trip while Daphne is filming her show. After encountering a lot of fake monsters, the gang finally arrives in New Orleans. They are soon invited by a young woman named Lena Dupree to visit Moonscar Island, her employer's home, which is allegedly haunted by the ghost of the pirate Morgan Moonscar. Although the gang is skeptical, they go with Lena, to whom Fred has taken a fancy. On the island, the gang meets Lena's employer Simone Lenoir as well as the ferryman Jacques and Simone's gardener Beau, to whom Daphne takes a fancy. They also meet Snakebite Scruggs, a ill-natured fisherman, and his hunting pig, Mojo. The gang sets out to prove that the "ghost" is a fake. Scooby and Shaggy are chased by Mojo and end up falling into a big hole, where they encounter the zombie of Morgan Moonscar. By the time the rest of gang comes to investigate, Moonscar isn't around. Simone invites the gang to her house to stay for the night. As the gang is dressing up for dinner, Shaggy sees the ghost of a Confederate colonel in the mirror; Simone explains that the island was a temporary headquarters for a Confederate regiment during the American Civil War. Due to Simone's cats, Scooby and Shaggy eat in the Mystery Machine, but find the food spicy and get some water from the lake, where an army of zombies emerge. Shaggy's bad driving gets the Mystery Machine stuck in the mud, forcing him and Scooby to flee on foot. Fred and Daphne find the Mystery Machine, but no sign of Shaggy and Scooby. They argue about each other's supposed love interests and come across Scooby and Shaggy. They manage to capture a zombie, which is revealed to be real. As the zombies swarm around them, the gang splits in panic. Elsewhere, Scooby and Shaggy discover wax dolls that look like Fred, Velma, and Daphne, and they play with them, causing their friends to undertake a series of involuntary actions for a short time until they leave after disturbing a nest of bats. Fred, Daphne, Velma, and Beau return to Simone's house and discover a secret passage under the staircase. They find Lena, who tells them that the zombies took Simone away. Fred, Daphne, Velma, Beau, and Lena find a secret chamber for voodoo rituals, where Velma finds footprints of Simone's heels and interrogates Lena about the story. Simone then appears, and she and Lena use voodoo dolls to trap the gang in the chamber. They reveal themselves to be evil cat creatures. Simone tells them that several centuries ago, she and Lena were part of a group of settlers who were devoted to a cat god. The vengeful Lena and Simone asked their cat god to curse pirates, who had chased the settlers into the bayou. Their wish was granted and they killed the pirates, but the curse caused the duo to become cat creatures permanently, requiring that they drain life forces to preserve their immortality. They also gave Jacques immortality so they had a ferryman to bring them more victims. The zombies' intent was to warn the gang to leave to escape their fate. Jacques finds and chases Scooby and Shaggy to drain their lives, but they accidentally tumble into the cave, interrupting the draining ceremony and distracting the cat creatures. Velma quickly unties herself and creates voodoo dolls of Lena and Simone to interrupt their ritual. When they are finally cornered, the cat creatures' curse expires, causing them to disintegrate, freeing the zombies' souls to rest in peace. Beau is revealed to be an undercover police officer sent to investigate the disappearances on the island. Daphne offers Beau a chance to guest-star on her show and discuss the adventure. The next morning, 
 Question: What does Lena and Simone have to drain from their victims to get their immorality?
Output: drain life forces