Julia (white) and her parents are spending the summer far from their Cornwall home, at the Uffle-Gent lighthouse on the island of Unst in Shetland, Scotland. Her dad will be automating the lighthouse, while her scientist mum is in search of a Greenland shark. Remarkably slow moving and long living, these sharks—Mum thinks—could hold the key to a breakthrough dementia treatment for humans. Missing home, Julia is happy to find a new friend in local boy Kin (South Asian). When Mum’s funding dries up without a shark sighting, though, Julia begins to sense mounting tension between her parents. Fixated on the sharks, Mum buys an extravagant camera and a rickety old boat without consulting the family first. Julia admires, even idolizes, Mum, but soon even she cannot ignore Mum’s erratic behavior; Mum is ill, and her manic episode takes a nearly fatal turn into a severe depression. Determined to salvage things by tagging a Greenland shark for Mum, Julia recklessly takes to the sea in Mum’s boat, making her way toward the coordinates of a reported sighting. Beautifully written, the story is honest in its depiction of the impact of parent’s severe mental illness on a child. Moody black and white illustrations evoking fog, water, and billowing clouds are shot through with splashes of brilliant yellow. (Ages 9-13)