Emma Sharpe is recovering from a shattering loss while her husband, Colin Donovan, is deep into his latest undercover mission. So they're grateful to enjoy a peaceful autumn weekend together on the southern Maine coast to celebrate Colin's brother Andy's wedding. But the peace is short-lived when Kevin Donovan, a marine patrol officer, receives a call to check on suspected food poisoning at a party aboard a yacht. Colin decides to tag along. He is surprised to recognize one of the victims as an undercover British intelligence officer, and it quickly becomes evident they're dealing with something very sinister. At the same time a valuable painting by Irish artist Aoife O'Byrne, a friend of Emma and Colin's, is missing from the yacht, and the connections make the investigation international and extremely personal.