Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nd4/4. Nxe5/4...Qg5

4...Qg5!
Accepting the gambit was a mistake, as Black now shows with the accurate 4...Qg5.

Attempting to hold on to the knight with 5. Nxf7?? will result in 5...Qxg2 in which White will lose either the rook, attempt to hold on to the rook and lose the queen with 6. Rf1 Qxe4+, or get checkmated by attempting to keep both the rook and the queen with 7. Be2 Nf3#.

Better for White is 5. Bxf7+, which loses a piece for two pawns but keeps White in the game.