In present-day West London, Imogen struggles to connect with her young son, preferring her stay-at-home husband to take the lead. Imogen is all edges: lacking maternal instinct, more invested in her work than her family, short-fused and brittle. At her husband's insistence, she agrees to take her son to the river to mudlark, only to watch in horror as he is dragged into the water, never to be seen again. As the police search unfolds and something dark and festering appears in Imogen's vision of the water's edge, her sanity is called into question. She forces herself to alter her story, believing that doing so will hold what's left of her family together. Instead, lies beget lies, and the frayed edges of her marriage threaten to unravel altogether.