1.d4 + ?

but 1...cd ep. !

1.e4 ? threat: 2.Sd7 #

but 1...fe ep. !

1.Rf6 ! threat: 2.Sd7 +

2...K:d5 3.Rd6 #

1...c3 2.d4 + !

2...R:d4 3.Bd6 #

1...f3 2.e4 ! threat: 3.Sd7 #

2...R:e4 3.Sf7 #

Dresden theme, en passant

The problem demonstrates the difference between capturing en passant (doesn't selfblock) and normal capturing (selfblocks).