The Wife Upstairs (Rachel Hawkins, 2021)

When Jane, a broke dog-walker newly arrived in town, meets Eddie Rochester, she can't believe her luck. Eddie is handsome, rich and lives alone in a beautiful mansion since the tragic death of his beloved wife a year ago. A man who seems perfect... Eddie can give Jane everything she's always wanted: stability, acceptance, and a picture-perfect life. A wife who just won't stay buried... But what Jane doesn't know is that Eddie is keeping a secret - a big secret. And when the truth comes out, the consequences are far more deadly than anyone could ever have imagined...