The Dodo, the Gryphon, and the Mock Turtle were on trial for theft. Exactly one of the three was guilty. Each was allowed to make an accusation (they could accuse themselves).
In addition:
User her powers of deduction, the Queen of Hearts announced, "I know who is guilty!"
Alice replied, "I also know who is guilty!"
It is well-known that both the Alice and the Queen are very logical. Which defendant is guilty?