Mystery Train

Mystery Train Island is the 21st island released on Poptropica.

Plot synopsis
Mystery Train Island takes place during the 1893 Chicago World's Fair. Here is the description from Poptropica: How do you solve a mystery when everyone is a suspect? It's 1893, and some of the world's brightest minds are traveling by train to the World's Fair in Chicago. But after a dastardly crime puts the fate of the Fair in peril, only you can piece together the clues and collar the criminal. All aboard for a whodunit that will keep you guessing until the last twist of the tracks!

Sneak Peek
Before it was released, you could play a sneak peek game for Mystery Train Island called "D.C. Diner". It's kind of like Diner Dash. You have to get people the food/drink they ordered, wash their dish and serve the next people in 1 minutes and 30 seconds. Also when someone is done 30 seconds is added to the clock.

Trivia

 * As of 16 August 2011, it is unknown of what the crime is (as seen in the description)
 * As Counterfeit Island, it a investigation crime island
 * It is unknown how you travel from Washington, DC to France in a train, since you have to cross water
 * In the luggage car, the hoverer from Astro-Knights Island is seen.