A crotchety old man goes to no end to get into Mexico with eight hundred thousand dollars in stolen money. He is faced with outwitting A deranged killer, Law enforcement, and a con woman.

Leaning towards:
“A crotchety old thief must outwit a deranged killer, a rogue cop, and a con woman in order to escape to Mexico with 800,000 dollars”

I took some liberties with your nebulous “law enforcement” — you get the idea.
Consider a holy grail amount of stolen money to up the stakes.

Make this yours, keep going!