Hazel Wong and Daisy Wells are taking a vacation across Europe on world-famous passenger train, the Orient Express--and it's clear that each of their fellow first-class travelers has something to hide. Even more intriguing: There's rumor of a spy in their midst.

Then, during dinner, a bloodcurdling scream comes from inside one of the cabins. When the door is broken down, a passenger is found murdered--her stunning ruby necklace gone. But the killer has vanished, as if into thin air.

The Wells & Wong Detective Society is ready to crack the case--but this time, they've got competition.