I don't think this counts as spoiler, but I'll de-spoiler it anyway.
Was the sealed move made under time pressure? Were either or both players under time pressure before this position?
Two moves each including the sealed move implies black has the last move. Can't see mate in two, so perhaps someone resigned or a draw was agreed? Then the problem is to figure out whether "resigns" or "offers draw" is included in Black's two moves, or if it's excluded from them and is white's third.
Could the sealed move have been a horrible blunder, like Q-b7 or Q-e4, made while the player was too tired? Nope, that would be immediate resign without even the second move. That move tempted me momentarily when I saw the rook on d5 guarding d6 for white, but confusing the colours like that is less likely with a real board.
Another tempting sealed move is Bxe6, after which KxB provides lots of scope for checks with threat of material gain. But victory isn't obvious, and black has scope for a nasty counter-attack. Perpetual check?
Bxe8 is slightly similar, but then 2.Q-b7 is not check, so black gets the initiative and captures the queen for victory on queening the pawn. Check at a4 and a7 at move 3 has the same outcome. So that's another blunder - though this time the move count is right for the resignation. In fact black's scope for counterattack is such that any non-check looks hazardous for white.
Absent a blunder, my best guess would be perpetual check. Black cannot break out without losing a piece; white cannot stop without handing black a winning counter-attack. But for both sides to see it through as early as move 2 seems optimistic. And if it's clear at move 2, why not at move 1?
Except, that seems too easy for one of yours. There must be a moment of inspiration somewhere there. Ho, hum, back to the drawing board.