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.