THIS IS WHAT HAPPENED by Mick Herron

Hidden away for years, no one missed Maggie.  She just didn't show up for work one day and no one questioned where she was.  It's hard to believe , Maggie could be deceived for years. She was, though, until her sister tried to find her.  Her sister could find no trace of Maggie.  Meredith, Maggie's sister, met Harvey in the coffee shop she had glimpsed Maggie hriugh the window.  Meredith became suspicious of Harvey and tricked him into leading her to Maggie.  I didn't particularly like this book. It seemed too far fetched or maybe the content didn't actually explain how the ending came to fruition.