This is pure genius - a mob of Irish-American gangsters with Lee Marvin at their head (as 'Nick Devlin') are called upon to leave Chicago for Kansas city, to rein in Mary-Ann (Gene Hackman) for outstanding debts of a pal of Marvin's - the latter is cold and hard but shows his soft side in relieving Mary-Ann of his other business interest, a young Sissy Spacek, groomed under Mary-Ann's sex-slave sideline to his meat packing business, of whom he sent one of Marvin's pals 's henchmen back as sausages! Marvin confidently walks into Mary-Ann's empire and kicks his ass, after a mauling of some of Marvin's men. A nice scene of Marvin's car being ground up in a harvesting machine, with a lot of nice(?) violence made this an action-packed gangster drama. Worth watching most definitely, personally, I think it's Marvin's best though little known (even better than his role as Reisman in 'The Dirty Dozen').
