Chess Opening Theory/1. e4/1...e5/2. Bc4/2...Bc5/3. Qh5/3...Nc6

3...Nc6??
The last move for black. He had not seen the threat of 4.Qxf7#.

Theory Table

 * 1. e4 e5 2. Bc4 Bc5 3. Qh5 Nc6??