Black to play. This position is from So-Nakamura, Ultimate Blitz Challenge, Saint Louis 2016. How did Black make a key breakthrough while also winning material? Answers to me at The Spectator by Tuesday 31 May or via email to victoria@spectator.co.uk or by fax on 020 7681 3773. There is a prize of £20 for the first correct answer out of a hat. Please include a postal address and allow six weeks for prize delivery.
 
Last week’s solution 1 Qxh7+

Last week’s winner Tim Leeney, Hartfield, East Sussex