In the real world, Hi and Mai are sisters. They live with their father and grandmother in Chinatown. In their imaginations, however, they are Oyster and Clam-shell, explorers from another world, an ocean inside the earth. They came through a hole at the bottom of a very deep lake and soon they will return, leaving their host family behind. Increasingly bizarre preparations for their return home threaten to tear their earthly family apart.
