A violent storm isolates Blackwood Hall from the outside world. When a charming stranger arrives seeking shelter, his presence unsettles the household - for Julian Mercer knows secrets that every guest and servant has fought to keep buried.
Before the night is over, Mercer is dead.
With the roads flooded and the telephone line cut, everyone in the house is a suspect. Inspector Gabriel Thorne must untangle their conflicting accounts, but Gabriel sees what others miss: a glass with the faintest difference in colour, an object fractionally displaced, a lie betrayed by one careless word.
Mercer did not come to Blackwood by chance. He had questions to ask, old wrongs to uncover - and one final secret worth killing to protect.
To identify the murderer, Gabriel must discover why Julian Mercer came to Blackwood - and which of its secrets proved worth killing for.