Veteran filmmaker Mary Stephen digs into her own family past to uncover the long-hidden origins of her Western surname, revealing a story of culture shock, colonialism, and contested remembrance.

Melanie returns to Hong Kong as filmmaker-in-residence at a university after living abroad for decades. She tries to redefine her cultural roots and affiliations, partly through the adventure of a tragic-comic romantic fantasy, partly through bonding with her young student Niki. Niki is making a documentary film with her mother about their family’s migration from China to their Hakka village in the New Territories. Melanie and Niki Both realise they are living with an original “molecule” that can’t be erased even after generations of dilution, the so-called “Memory of Water.”