The Marshall Trap is a chess opening in Petrov's Defence named after Frank Marshall.
The trap
1. e4 e5 2. Nf3 Nf6
:The trap begins with Black playing Petrov's Defence.
3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Bd6 7. 0-0 0-0 8. c4 Bg4 9. cxd5 f5 10. Re1? (see diagram)
:White should play 10.Nc3 instead.
10... Bxh2+!
:An unexpected blow.
11. Kxh2
:If 11.Nxh2, then 11...Bxd1.
11...Nxf2
:Black forks the white queen and bishop, forcing the queen to move.
12. Qe2 Nxd3 13. Qxd3 Bxf3 14. Qxf3 Qh4+
:Followed by 15...Qxe1 winning the e1-rook. Black has a winning material advantage.