Frank the Rat revolves around the deep but fragile bond between a brother and sister. Billy and Lisa were very close as children but, because of a troubled family history, they haven’t seen each other in years.
Billy (Derek Cecil) lives in a run-down industrial neighborhood in Brooklyn. He doesn’t have a real job, or a place to call his own. His landlord lets him stay in the basement in exchange for taking out the garbage and mopping the floors. His best and only friend is the landlord’s 14-year-old son.
Lisa (Fiona Dourif) appears to be doing better, but that’s just on the surface. The truth is, she just ran out on her fiancé, and that’s only the beginning of her problems.
One day Lisa shows up on Billy’s doorstep with a plan to save them both: hit the road together and find Frank, the father they haven’t seen in twenty years. Along the way, they meet a collection of uniquely American characters and have adventures both good and bad. And, naturally, nothing goes according to plan.