Royal defence against an almost invisible ghost

The trick is to see the ghost so that you know what you must defend yourself against. Even then it's hard.

I think the ghost is Monster_Melons but I don't know how to defend against him. Somebody help me!

I will show you the ghost. Here, you must play for your opponent. You must play for white while you see the board from black's point of view. When you solve this puzzle, you will know where the ghost is. The third move has more than one solution, but you will quickly see the right move if you make the "wrong" move, so no reason to worry about that. Just try the third move without thinking too much when you get that far.

Here is the ghost again. Play for your opponent to obtain the same as last time.

Well, it's almost Christmas. I'll probably be forced to rewatch "Ghost" and I'll do that extra carefully this year. Hopefully it gives me a clue because your comments only increased my confusion  Don't worry, I'll get over it!