Their Little Secret — Mark Billingham

A woman's suicide puts a detective on the trail of a cold-hearted con artist: “Outstanding . . . a maximum of suspense” (Publishers Weekly, starred review).
 
When DI Tom Thorne is called to the site of a suicide, he expects to be in and out in no time. But when he arrives at the Underground station where a woman named Philippa Goodwin threw herself in front of a train, he inexplicably senses something awry and feels compelled to dig deeper. He soon discovers that she was the victim of a callous con man who preys on vulnerable women -- and whose deception plunged Philippa to her end.
 
Thorne enlists DI Nicola Tanner to help him track down the swindler and bring him to justice. But the detective duo gets more than they bargained for when a young man's bludgeoned body turns up on the shore of a nearby seaside town and the two cases come together in a way that neither of the detectives could have foreseen . . .
 
“A fantastic thriller . . . a gripping plot and lead characters of remarkable depth. Billingham is a multiple-award winner, and his books have sold more than six million copies. Readers who grab this one but aren't familiar with its predecessors will be seeking them out. A series to savor.” ―Booklist (starred review)
 
“Billingham is a world-class writer and Tom Thorne is a wonderful creation.” ―Karin Slaughter, bestselling author of the Will Trent series