When the body of Oscar Lomas, an experienced hiker, is found at the bottom of a remote cliff in the Peak District of England called Cloud Drop, all the signs--including the "Sorry" note he left behind for his wife, Beth--point to suicide. Plans for the funeral begin, but Beth cannot accept that her husband took his own life. As she sets out to discover what really happened, Beth soon realizes that the safe, protected life she thought she had was nothing of the sort, and that Oscar had kept many secrets from her--secrets that involve even close family and old friends. It turns out that he had enemies--and perhaps she did too, even if she didn't know it. As the troubling revelations keep coming, Beth has to focus on solving one mystery if she is to reclaim her own life: who killed Oscar Lomas?