Scooby Doo: Ten Years Later is a movie detailing an alternate timeline set ten years in the future, where Mystery Inc has broken up. It features them having to band together again to solve a mystery on Fairytale Island after being invited, while clashing with a newer group called Investigators Corp, which consists of analogous to the gang.
•Scooby Doo (TYL): Left by Shaggy at a animal shelter, ten years later Scooby is an old dog who looks after his teenage grandson Scooby Doo III. He has lost all faith with the old gang, particularly Shaggy. Due to his age, Scooby is facing death and, with advice from his grandson, decides to solve one last mystery.
•Shaggy Rogers (TYL): Now a loving father to two children, Shaggy was the first of the gang to leave, believing that he had to stop living in his childhood as part of Mystery Inc. This causes the breakup of the team. Thought deciding against rejoining Mystery Inc, when he learns his kids have gone missing he instantly heads off.
•Daphne Blake (TYL): Daphne is now a movie star with the desire to forget her life during Mystery Inc, but is struggling to forget Fred. When she is approached by Aaron Lucas, she leaps at the chance to be in a mystery solving movie, with her cameraman George coming along for the reunion.
•Velma Dinkley (TYL): Velma is a government scientist sent with government agent Dan Richards to solve the possible criminal connection on Fairytale Island. She is regretful about how things ended ten years before and dearly misses her old friends, especially Shaggy, who she harbours feelings for.
•Fred Jones (TYL): Now the owner of a unsuccessful hunting club that sells harmless traps, having decided to put his trap making skills to good use, he is trying to move on with his life. He is initially hesitant to meet his old friends, especially Daphne.
•Scrappy Doo (TYL): Scooby Doo's nephew, Scrappy is now a member of Investigators Corp and fills in the role held by Scooby. Unlike the loveable, idealistic and fun loving Scooby who can't speak properly however, Scrappy is cynical, manipulating and mean while being able to speak properly.
•Steve Smith (TYL): A arrogant young detective, Steve is the leader of Investigators Corp, filling in Fred's role. Unlike Fred, who is understanding and caring while knowing his limits, Steve is self-centred and cocky, believing he is better than every one else. The only reason he works in a group is to not do any of the actual thinking when solving a mystery, as he only likes the action.
•Rebecca Donaldson (TYL): A former scientist, Rebecca fills in Velma's place as a member of Investigators Corp. While Velma is willing to slow down and explain things to her friends, Rebecca looks down on those she seems inferior, including her teammates, and often refuses to explain her conclusions or plans.
•Jason Long (TYL): Originally a simple pizza deliverer who was good at noticing things, Jason is a member of Investigators Corp and fills in Shaggy's role as the glue that stops the many abrasive qualities of his teammates at bay. While cynical, vengeful and sometime cold, Long is still the only member of Investigators Corp who shares a quality with his Mystery Inc counterpart: he honestly cares about his teammates and helping others.
•Suzy Winter (TYL): An actress with little to no compassion, she fills in Daphne's role and also supplies much of the money Investigators Corp. While Daphne is clever and resourceful while having a good heart, Suzy is dumb and dependent while caring only about money, only joining Investigators Corp for fame.
•Randy and Holly Rogers: The son and daughter of Shaggy Rogers respectively, they have inherited an equal half of Shaggy's dominant qualities. Randy is childish, if a bit cowardly, while Holly is brave, but is always hungry. When they disappear on Fairytale island, Shaggy heads off to find them.
•Aaron Lucas: The owner of Fairytale Island, he wants the gang to solve his monster problem.
•Dan Richards: Dan Richards is a secret agent that goes with Velma Dinkley to investigate the island. He is very cynical and finds Velma and her old friends to be stupid and childish.
•George: Daphne's camera man, a running gag in the film is for him about to tell people his last name, but always ends up being interrupted.
In an abandoned factory, the gang capture the pterodactyl ghost. However, while packing up Shaggy announces he is leaving the gang. When asked why by the shocked group, he answers by saying that while it is fun to run around trying to find clues and foil a crime, after nearly eight years of doing it since they were kids, Shaggy has finally realised that the rest of the world won't stop for them and one day, they will find themselves to have wasted their whole lives. After tearfully saying goodbye, Shaggy leaves with Scooby choosing to follow him.
Ten years later Shaggy, now going by his first name Norville, is a successful businessman and single father of two eight year old twins Randy and Holly. Despite his happy exterior, his coworkers all agree that his actions seem faked when he is not with his kids and he is bullied by his boss.
Meanwhile, it is shown that Mystery Inc soon broke apart due to Shaggy leaving with Scooby. Fred, realising he is good at making traps, decides to open a hunting club that sells traps and some weapons that don't harm animals; however, it is unpopular and he faces losing it. Velma is working as a scientist, investigating a powerful chemical that can enable feats of superhuman proportions; despite her high paying job and stable life however, Velma painfully misses her life as part of the gang, even sometimes mimicking events from the past. Daphne is now a famous actress who has ignored all comments about the gang; despite this, she still loves Fred and hates what happened to Mystery Inc.
Scooby Doo ended up is an animal shelter due to pestering Shaggy about his decision, where he fathered a litter of five kids, all who ended up adopted, leaving him with his rock and role punk grandson Scooby Doo III, or Scood as he is commonly called. While everyone else got adopted, Scooby never did due to refusing to join a new family, as he still misses the gang, despite obviously hating them. Due to his age, Scooby is now very old and is possibly near death.
One day, Daphne is approached by Aaron Lucas, the owner of Fairytale Island, who wants her and Mystery Inc to get back together and solve the mysterious events at his theme park. Despite declining, Daphne's boss tells her she will be let go from her acting contacts if she doesn't go, as a televised reunion will bring lots of money. Velma, after being asked by Lucas, is also ordered to go by her superiors, as the chemical she was working on has been stolen and might be at Fairytale Island. Fred, after being offered $20,000 to come, reluctantly agrees and Shaggy, upon learning from his mother that his kids have disappeared on the Island, also agrees. For the first time in ten years, the four are united and are forced to go and find Scooby Doo, as he is needed to complete Mystery Inc.
Fred, Daphne and Velma are shocked that Shaggy got rid or Scooby and are equally gob smacked by how lifeless Shaggy seems. When they all learn how Scooby never left the animal shelter, despite after all his kids and grandkids left, leaving him with Scood. Despite the fact they begged him, Scooby at first refuses, but Scood talks to him privately and convinces him that his grandfather has been waiting for this day for years.
The five reunited, they head to Fairytale island despite struggling to speak to each other. However when they arrived they discover that due to their initial hesitation the owner got worried and hired a different crime solving gang in case Mystery Inc failed. The group is called Investigators Corp and include Steve Smith, Rebecca Donaldson, Jason Long, Suzy Winter and to their surprise Scrappy-Doo. Unlike the traditional Mystery Inc who often relied on talent and luck to solve mysteries, Investigators Corp is far more profession and relies on advanced technology.