The Blue Iguana (1988)

Two overzealous psychopathic US tax collectors blackmail bounty hunter Vince Holloway into stopping an illegal transfer of 20 Mio. dollars from a Mexican tax paradise into the USA. So he arrives in Diablo, where life isn't worth a penny. It seems impossible to raid the heavily guarded bank. He has to assure himself of help of the barwoman Dakota and a little boy.