What could be more mundane than a midlife crisis? For Leo Spivak (Peter Riegert), there’s no deadpan road trip to mend the broken flowers of his past, no fever dream of a high school cheerleader covered in rose petals. No flowers at all, really; just solitaire on the office computer and a choice between a pine box and a mahogany casket. Riegert’s keenly observed directorial debut mostly staves off genre clichés and histrionics, as Leo contends with an ailing father, a passionless marriage, and a twentysomething protégé who’s after his position in a marketing firm. A self-proclaimed descendant of “bad Jews,” the kind of sacrilegious nonbelievers who built the biblical golden calf, our affably pathetic nonhero remains content with his status as a faithless middleman. But mortality beckons, and a Mourner’s Kaddish provides a breakthrough. King of the Corner is an average film starring an average character actor, but maybe that’s the point. This is a story about the benefits of just showing up. Even at its most sentimental, Riegert’s pet project possesses a lived-in integrity that nearly offsets the staleness of the material.