Find the key move to mate in 2. Careful, like always there are a bunch of very tricky looking tries!

Let's first analyse the variations after the key 1.Nfd2! 2.Ne4# is threatened. There are only two defenses: Nd6 and d5. What happens after 1...Nd6?

Now, what happens after 1...d5?

Let's investigate the faults in the tries now. What is the issue with 1.Nc1? The threat obviously is 2.Na2#

How do you refute 1.Nd4?

How do you refute 1.Ng3?

Finally, what is your refutation to 1.Ne3 (th: 2.Nd5#)?