Three generations grappling with a life-changing experience during one day of a vacation in Sintra, Portugal, a historic town known for its dense gardens and fairy-tale villas and palaces.

Based on the novel by Hannelore Cayre, the story centers around Patience Portefeux, an underpaid, overworked French-Arabic translator in charge of phone surveillance for a narcotics police unit. When she realizes she knows the...