the most ridiculous criminal plan in the history of movies

oh wow where to begin?

Kill a guy, make it look like suicide:
Hmm, ok but pretty risky.

Predict that the widow would fly the dead body home, on the exact airline and flight you will be working on:
Ok this is already retarded.

Somehow make a girl disappear on a busy flight without anyone noticing:
Possible but extremely risky and definitely not something you will rely on for an elaborate scheme.

Predict the mom will go crazy enough to sneak into the storage cabin to open the coffin which contains the bombs:
Yeah right

Pretend the woman is demanding money without her finding out and know for sure they will give her the money:
Come on!

And if all this goes well (everything will have to go perfectly way for this to work) you move to some island and live happily ever after without the authorities wondering how you suddenly obtained millions of dollars

I put the odds of all this going perfectly well at 1 in 100, AT BEST which is way beyond the realms of suspension of belief.