You're White, it's your move, and your opponent has just offered you a draw. What do you do?

The first thing to do, naturally enough, is to suspect his motives. Has he spotted some devastating discovered check with the knight? Probably not, since any knight move must be to a black square, where anything it attacks will be on a white square, so the black queen and knight are safe. On the other hand, 1.Ne3+ forces 1...Kg3 (1...Kh4 2.Qg4 mate or 1...Kh2 2.Qf2+ are fatal for Black) when only the presence of the white queen on f5 stops White from delivering a devastating knight fork.

So perhaps, before accepting the draw offer, we should pursue this line: 1.Ne3+ Kg3 2.Qg4+ Kf2 3.Qf4+ Ke2 but now what? Well, we can continue 4.Qf1+ since the knight is immune from capture (4...Kxe3 loses the queen to 5.Qe1+) so let's continue: 4...Kd2 5.Qd1+ Kc3 6.Qc2+. Now we seem to be getting somewhere since 6...Kd4 allows the knight fork on f5 that we've been waiting so long to play. So Black must play 6...Kb4 when 7.Qb2+ leads to mate after 7...Ka5 8.Nc4+ Ka6 9.Qb6. Ah, but Black plays 7...Nb3 instead shielding his king and getting out of trouble. Perhaps we'd better take that draw after all. Right?

Wrong! 8.Qa3+!! Kxa3 9.Nc2 is mate. (From a study by Leonid Kubbel).