Death Comes First — Hilary Bonner

If you can't trust your family, where do you turn . . . Joyce Mildmay's life is torn apart when her husband Charlie is killed in a tragic yachting accident. Though financially secure, Joyce is left to raise their three children by herself within Tarrant Park, a secluded gated development set in the rural countryside outside of Bristol.
Six months later a mysterious letter arrives on her doorstep which turns her shattered world upside down. The letter is from Charlie, delivered belatedly in the event of his death, and contains a sinister warning that Joyce's father, Henry Tanner, and the family business is not as it seems. For their children to be safe, her husband pleas, she must leave their home and never look back.
Confused and alarmed by this message from beyond the grave, Joyce decides instead to stay and unearth the truth. But what she learns reveals a trail of intrigue and deception that stretches back through the years. It seems that death is just the beginning. . .