McMahon does a nice job of playing with readers’ expectations in this captivating thriller set against the murky underbelly of the Internet. Mason Grant became financially independent as the result of a tragedy, netting millions in a settlement after his wife and daughter were killed by a drunken truck driver whose employers were aware of the trucker’s prior DUI convictions. Mason has settled in Hawaii, but his placid life in a house by the beach is roiled when Frederick Iverson, a financial manager, asks his help. Iverson’s 24-year-old daughter, Michelle, disappeared two days earlier, and he suspects a connection to her involvement with an online S&M community, Dark Chateau. Although not a PI, Mason agrees to help and finds Michelle’s alluring 27-year-old stepsister, Tracy, useful in his quest to track down the people Michelle interacted with online. His relationship with Tracy becomes increasingly intimate as their inquiries progress. The author inserts an unexpected development midway that makes the ending twists even more unexpected. (BookLife)