Last week I left you with this position from Artemiev-Hracek (2019 European Championship).

White crashed through with 25. Rxg7! Kxg7 26. Rg3+ Kh8 27. Nxd5! Nxd5 28. Bh6 Bf6 29. Qxf6+! and Black resigned in the face of impending mate.

An impressive combination, sacrificing a rook, followed by a knight, and finally a queen.

Bob and Carol have been playing chess at the club again. Returning from the bar with a pint, I saw this position on the board.

I advised Carol that next time she played the Alekhine Defence she should move her knight to d5 rather than leaving it to be taken. Then I spotted the missing white bishop. I asked Bob if he’d forgotten to set it up at the start of the game, but he assured me he hadn’t. Can you tell me how they reached this position after Black’s fourth move?