Folkestone, 1921. Newly-wed Maude Brent couldn't be happier.
She'd like it if her husband Lionel wasn't quite so overprotective but, as it's proof of his affection, she can't bring herself to mind. When her much-loved elderly housekeeper Aunt Biddy starts to grow forgetful, Lionel suggests that Maude hire a companion to take the load off her - and he knows just the girl.
Initially reluctant, Maude trials the young and bubbly Alice, and soon it's as if she'd always been part of the family. But when Lionel takes Maude on holiday to the seaside town of Hastings, tragedy strikes and he disappears.
A body is washed up on the seafront and a distraught Maude fears the worst - but it's not Lionel, and when a ransom demand is sent to her, she is reassured to know he is alive. However, things aren't as easily solved as she'd hoped, and Maude discovers she's at the centre of a twisted plot to defraud her...