Adapted from Dean Fleischer-Camp and Jenny Slate's online short film series, Dean directed and starred in a human documentary director also called Dean, who moved into a rental house in Airbnb and found a resident-a shellfish Marcel, his grandmother Connie, and his pet: a pile of fluff called Alan. Marcel is voiced by Jenny Slate and Connie by Isabella Rosselini. Marcel and Connie were originally members of a large shell family, but they now live alone because of a mysterious tragedy. Dean began filming their daily life, and as a result, it quickly became popular on the Internet, and the life of one person with two shells was changed forever. Will this help Marcel find its lost family?