Velma, a research assistant for NASA, brings Daphne, Shaggy and the dogs out to dinner at the White House where they are discussing the new space station Velma helped with. To everyone's surprise, the ghost of George Washington comes.
Freddie joins Daphne, Shaggy, and the dogs in attending the Mystery Solvers Contest in London at the famous 221B Baker Street. Along with other detectives, they must solve the "Mystery of the Blue Carbuncle. Sherlock's unsolved case.
All the customers are scared away by the ghost of Col. Beauregard, who is looking for Magnolia. She believed he stole her priceless emerald necklace, so she refused to marry him all those years ago
Next stop on the Cheapo European Tours: Denmark, where it seems there is something rotten in Denmark as the kids run into the ghost of Hamlet at the Hotel Hamlet they are staying in. The ghost wants to let the kids know something though.
The gang is hired to interview the reclusive Norma Deathman, who lives with her monstrous servants. While lost and trying order a pizza, the gang meets two twin inventors working on a secret project that could "change mankind".
