My Rating: 4.6
Selena and Martha don't know each other but they both have sordid secrets. They are commuting home on the same train and both confess - Martha that she is sleeping with her married boss and Selena that she has seen her husband on the nanny cam having sex with their nanny. They part ways, presumably to never meet again. Then the nanny disappears and Martha starts texting Selena saying they should meet.
This is a quick paced fun thriller / whodunit. Like most of Unger's thrillers, I find you need to suspend logic and reality and just enjoy the ride.