A book has disappeared from the classroom shelf. Joel, Ethan, Grace, and Liam were the only ones in the room. One of them took it. Exactly one of them is lying.

1. Joel says: "It wasn't Liam."
2. Ethan says: "Liam is innocent."
3. Grace says: "Neither Joel nor I took the book."
4. Liam says: "Joel is innocent."