As Nate the Great sets to work on his first international case, he searches for a lost "something" and saves the King of Sweden from a troublesome traveler.
When Rosamond looks into her crystal ball to read Nate the Great's future, she sees a new case for him to solve--her money box is missing and she wants him to find it.
Even a deep snow the week before Christmas can't keep Nate the Great and his dog Sludge from finding the special card sent to Annie's dog Fang by his mother.
Nate the Great and his sleuthing dog, Sludge, must become detectives and investigate the case of the missing pink piece of paper that has on it the perfect name, which Esmeralda came up with, to call Rosamond's pet concert.
"Nate the Great and his dog, Sludge, would like to take a break from detective work, but new cases--cases they do not want--await them"-- Provided by publisher.
While traveling on the train to San Francisco with his cousin Olivia's owl, Nate the Great and his dog Sludge must use all of their detective skills when the owl suddenly disappears.