Ori’s holidays are an endless series of elaborately awful meals cooked by her one-time stepfather Dave’s latest bride. Attended by a loose assemblage of family, Ori particularly dreads Grandma Elving—grandmother of Dave’s fourth wife—and her rhapsodizing about the Christmas she worked at Woolworth’s in the 1950s. And, of course, she hates being condescended to by beautiful, popular Sloane and her latest handsome pre-med or pre-law boyfriend.

But this Christmas is different. Sloane’s latest catch Lassiter is extremely interested in Grandma Elving’s boringly detailed memories of that seasonal job, seeing in them the hallmarks of a TFBM, or traumatic flashbulb memory. With Ori’s assistance, he begins to use the older woman in an experiment—one she eagerly agrees to. As Ori and Lassiter spend more time together, Ori’s feelings for him grow alongside the elusive mystery of Grandma’s past.