It Could Have Been Her by Lisa Jewell

In her fifties, Jane lives with her dogs at the estate where she grew up-- Rosebery Hall in Dorset, which is falling down and needs tons of maintenance and repairs. Jane knows in her heart she must put in up for sale. Otherwise, she has lived quite a comfortable life, twice-divorced with stepchildren she adores, but never having had a job. This idleness in part is what causes her to become overly involved in reuniting a dog she finds on her land with its owner. When Jane arrives at the home in the Vale of Heath, northwest of London, she realizes she recognizes the house from her past. After dropping off the dog, Jane is unable to get the home out of her mind,, nor the disappearance of the young woman who was seen with the dog near Jane's Dorset home. It Could Have Been Her follows Jane and her stepson Dexter as they attempt to find the woman, along with the backstory and what's going on in the London house now. A great read-alike for Jewell's The Family Upstairs, Liz Nugent, and Erin Kelly.