The sea cucumber resists categorization - it seems not quite animal, not quite vegetable. In Namako: Sea Cucumber, Ellen, a ten-year-old multiracial girl, no longer a child, not quite a teenager, finds herself exploring an unfamiliar world of spirits and ancestors, ghost stories and secrets.

Leaving the United States, Ellen and her family travel to Japan to care for an ailing grandmother Ellen has never met. In Tokyo, Ellen is sent to stay with and learn from her seemingly disapproving grandmother. When her father buys a house in northern rural Japan, Ellen and her grandmother rejoin the family. While there, Ellen's life changes rapidly - she discovers a talent for art, gains a best friend, and grows to love her grandmother.

Honoring a last request, Ellen and her mother journey with her grandmother to their ancestral home. There, finally, Ellen begins to integrate her family's history with her own future.