Missing You

I have read and enjoyed several of Harlan Coben's books, including some of his Myron Bolitar series. The protagonist of this book is Kat Donovan, a NYPD detective who has lived a solitary life ever since her dad was murdered and her fiancé at the time subsequently left her--nearly 20 years ago. Best friend Stacy takes matters into her own hands and puts Kat's profile on a singles dating web site. Kat is stunned to find a picture of her former fiancé, Jeff, on the website, indicating that he is widowed with one child. When she tries to contact him, sharing the video to a song that was uniquely theirs, he seems strangely unaware of its significance, and cuts off their contact, saying he needs to move on. In the meantime, Kat is contacted by a young man who says his mother is missing after having gone off for special vacation with a man she met on line--the same man Kat saw as her former fiancé--only using a different name. The young man, Brandon, is a computer programmer and hacked the website to track down Kat and ask for her help in finding his mother. What reveals is, of course, an elaborate plot to lure unsuspecting and financially well-off singles into a trap where they are held prisoner in underground boxes and psychologically, or sometimes physically, coerced into turning over all their financial information to their captors. Kat is thrown into a race to find the perpetrators before Brandon's mother joins the pile of corpses at a remote Pennsylvania farm. In the process, she finds Jeff, who has indeed changed his name, and learns why he really left after her father's death.  A fairly surprising twist in that part of the plot.