A long-awaited marriage in 1888 Maine has to wait for the solution of a murder.
As his wedding day approaches, Dr. Ben Northcote is called away to lonely Keep Island, home of his wealthy, reclusive friend Graham Somener. His fiancée, reporter Diana Spaulding, thinks her biggest challenge will be keeping peace between their respective mothers, redoubtable ladies of eccentric character. But she’s wrong. Somener has allowed his old family friend Serena Dunbar to dig on the island in search of artifacts to prove that Keep was the site of a pre-Columbian wreck of European explorers. Ben finds her crew suffering from morphine poisoning and lucky to be alive. When charismatic private eye Justus Palmer suggests that something illegal is going on at Keep, Diana, who hasn’t heard from Ben in three days, packs a bag and heads out. Ben’s suspicion that the diving accident that killed a member of Serena’s crew was actually murder is opposed by Serena and Somener, who suffered from terrible publicity when a building he financed collapsed and killed several people. Suspecting that Serena is a confidence woman and fortune hunter, Diana and Ben set out to investigate her background and protect Somener, who plans on marrying her. They chase a gaggle of wild theories before discovering the truth.
Emerson’s fourth and final tale of the sleuthing pair (No Mortal Reason, 2007, etc.) is both historically interesting and suitably mysterious.