Checkmate Puzzle #2

This combination is a really interesting one.  White is up a pawn and has an attack, and sooner or later should win the game.  But the way to win it is a bit surprising.  Hope you enjoy this one.  I have posted it as a mate puzzle.  However, Black can avoid it by playing a different first move which will leave him at a clear disadvantage. 

Here's an alternative:

I hope this was instructive.  Good luck in your chess.