The answer is the surprising 1.J9!, which forces black to capture with 1...H8* or block with 1...H10. If black captures, then: 2.H10,J9 3.K10,G7 4.J5,F8 5.G9 wins. If black blocks with his second move, then 2.H8 forces a pair along the same diagonal. Black is unable to stop White from getting the fifth capture by White's fifth move.