Whackers (1970)

Thad, an unarmed grocery store security guard, becomes a tyrant obsessed with absolute authority to the dismay of Rose, a regular customer and Thad’s only ally. Meanwhile, separated father Wally becomes engrossed in a fringe conspiracy theory and begins a legal battle to regain his freedom and custody of his children. As both men descend into increasingly dangerous behavior, a slow night at work becomes a battleground for life, liberty, and the pursuit of power.