Lost in the moment and found

Young Antoinette has lost her father, metaphorically speaking, which means she will not find him in the shop where lost things go: he will never be sitting there among the favorite childhood toys and missing socks and misplaced headphones. Then, "Antsy" finds she has lost herself, literally, and must search through many worlds and doors to escape the shop and discover, as all must, that childhood and innocence cannot be retrieved once they are gone.