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While trick-or-treating with his cousin Scott and a friend when he was little, Fred has a scarring experience when he is ambushed by an evil witch near an abandoned cabin. Several years later, Fred and the gang run into the very same witch on Halloween night in another town. As the gang attempts to solve the mystery of the witch, they must also convince Fred that he is incorrect in his belief that a mystery cannot be solved on Halloween night.
The gang travels to Britain in 1843-ish and runs into Scrooge who claims he was attacked by the ghost of his partner Jacob Marley and that three more ghosts are coming. The gang agrees to solve the mystery but Velma wonders if she has more potential than just solving mysteries.
With Fred not sleeping the gang decides it is time for a vacation. However their relaxation is short lived when a monster shark terrorizes the beach. The gang must solve the mystery whilst making sure Fred relaxes and doesn't get involved
When Scooby falls sick, the gang immediately rushes him to the hospital, only to discover it is being haunted by a werewolf. The gang must help Scooby and solve the mystery.
The gang heads to a renaissance fair from Velma's childhood and must act out the middle ages. A mystery is revealed when the spirit of a jester begins attacking the fair and the gang must quickly come to the rescue.
Shaggy and Scooby, sick of the monsters and mysteries, leave the Mystery Gang.
The gang decides to go to a dog show in New York, but they soon discover a mystery. With Fred undercover, Scooby trying to win the respect of other dogs, and Velma and Shaggy switching personalities, it's going to be a tough case to crack.
The gang is on a 3-day trip on a train, but when 8 monsters from different parts of the world appear, it's time for action. The monsters are the Grim Reaper, a Mummy, Tzitzimitl, Haniver, a Manticore, Hemogoblin, Tengu, and Tarasque.
Fred tries to solve a 700-year-old mystery in Japan; Daphne becomes a viral sensation.
Velma runs for mayor to bait the ghost that has returned to a town and scare the mayoral candidates.
A virus infects an asteroid mining crew one by one, turning them into evil skull-headed aliens.
To escape a snowstorm, the gang checks into a creepy hotel run by a man with strict rules.
The gang tours an old Hollywood Studio, but they soon uncover a mystery concerning the ghost of a silent film comedy star who has returned to make sure his recently discovered final film is never seen.
Fred gets to live out his childhood dream of being a stage magician when a mutant rabbit monster terrorizes a magic club.
The gang gets trapped in an ancient Greek palace, where they must find a scroll to escape.
Shaggy is surprised to see his old childhood first crush has become a goth; embarrassed that he hasn't changed at all, Shaggy attends a goth party with the gang.
The gang gets caught up in international espionage when they cross paths with British secret agent, Jenny Vex, and must help her complete her dangerous mission.
Fred's worst nightmare comes true when an evil spirit possesses the Mystery Machine and turns his beloved van into an unrelenting monster.
Daphne brings the gang to a fancy ice hotel where a new exhibit of ice age artifacts is opening; things heat up when a frozen Ice Man goes on a rampage inside the hotel.
The gang heads to Shaggy's beloved grandmother's Florida retirement home, where they learn a crazed ape man has been frightening the elderly residents.
