Whats going on here?

On Dan Heisman.com I learned of an exercise called the "Stoyko Exercise." Named after named after FM Steve Stoyko, the exercise has you looking at a complicated position for an hour, writing down all the probable lines you see, and at the end of the line, write your evaluation of the final position. Once you are done, take you lines to a computer, strong player, or coach and go over your notes to see what you missed, mis-evaluated, or overlooked. 

I decided to give this a whirl, and I chose the following position:

On first glance, you can see a couple of things, first: Both kings are not very safe. Black has two pieces hanging. Whites rook is pinned to his queen. Black is a pawn up, but that does not matter very much at this point. My first thought was 1.Bxd7. capturing the bishop, threatening the rook, and the g3 knight is still hanging. But then I discovered that, if the bishop moves, then black has Nf1+! Exclam! after Rxf1 black plays Qxg2 mate. So, taking the bishop is not the best option. I then thought about Kxg3, taking a knight, but after Bxg4 hxg4 Rxc2 things get complicated, and white must use perpetual to survive.

This was not a easily won for white as I thought it would be! I was getting desperate. I looked at other ideas, such as Bf3, Qh4, and and Rd1.

I overlooked the perpetual, and decided on 1.Rd1 I then switched on my engine, and lo and behold 1.Rd1 was the top choice! I was on top of the world... for about 5 seconds. A new move crept to the top, a move that was winning for white. Try to see if YOU can find this move:

If you solve the puzzle, click solution and go through the moves again to view my comments. Thanks for reading!