During their voyage through Sydney, the Mystery Inc. gang, including Scooby-Doo, [Frank Welker], and Fred Jones, [Frank Welker], heads to a music contest set at Vampire Rock, an outback landmark whose name nods to a mythic Australian vampire known as the Yowie Yahoo. On arrival, they reconnect with the Hex Girls—Dusk, [Jane Wiedlin], Luna, [Kimberly Brooks], and Thorn, [Jennifer Hale]—and meet the festival organizers Daniel Illiwara, [Phil LaMarr], and Russell, [Michael Neill], along with Daniel’s grandfather Malcolm, [Kevin Michael Richardson], who doesn’t hide his disapproval of the event. They also learn that a rival band, Two Skinny Dudes, is vying for the top spot. When a performer is kidnapped by vampires, scaring off several contestants, the Mystery Inc. team realizes this goes beyond a simple scare. Daniel and Russell recount the legend of the Yowie Yahoo and reveal that a former act called Wildwind was turned into vampires, supposedly haunting Vampire Rock ever since.
To smoke out the truth, Fred Jones, Daphne Blake, [Heather North], and Velma Dinkley, [Nicole Jaffe], enter the contest while Mystery Inc. splits up to follow different leads. Jasper Ridgeway, [Jeff Bennett], Wildwind’s former manager, bands with his current group, the Bad Omens, raising suspicion about their intentions and whether Ridgeway is scheming to push his own clients into a dramatic comeback. Shaggy Rogers, [Casey Kasem], and Scooby-Doo linger by the food stalls, only to be knocked off their feet when Wildwind targets the competition. The trio of Daphne, Fred, and Velma unearth clues in Ridgeway’s trailer—where mementos from Wildwind hint at a darker motive—before vampires close in and force a tense escape.
Chasing Wildwind into nearby caves, Shaggy and Scooby stay outside while Fred, Daphne, and Velma venture inside. They stumble upon old film gear and are soon chased out by the rising threat of the vampires. They dive into a pool to dodge a pursuing pack and manage to save Scooby-Doo from a pack of dingoes, who briefly disrupt the predatory advance. The group faces a direct assault from the Yowie Yahoo, but Scooby-Doo’s collar reflects the dawn light, weakening the bloodthirsty threat. Wildwind pushes the confrontation, yet the gang, aided by Daniel, corners and corners them until the true culprits emerge. The unmasking reveals Russell and Two Skinny Dudes in a calculated bid to revive Wildwind’s career, using costumes, a hologram of the Yowie Yahoo, and a scheme that leaves several contestants stranded on a Great Barrier Reef dive excursion. The Hex Girls are left for dead by the schemers, but Malcolm returns them to safety while Wildwind is taken into custody. Daniel declares Mystery Inc. the contest’s winners by default, and the group, joined by the Hex Girls, delivers a triumphant, celebratory performance.
