Apples Never Fall by Liane Moriarty

The Delaney family love one another dearly - it's just that sometimes they want to murder each other . . .
Joy Delaney and husband Stan have done well. Four wonderful grown-up children. A family business to envy. The golden years of retirement ahead of them.
So when Joy Delaney vanishes - no note, no calls, her bike missing - it's natural that tongues will wag.
How did Stan scratch his face? And who was the stranger who entered and suddenly left their lives? What are they all hiding?
But for the Delaney children there is a much more terrifying question: did they ever know their parents at all?