Folded. Hunter Grant series, #3

Notes asking for help folded into tiny origami shapes and found outside a city apartment building, a physics textbook with tiny writing between the lines and a woman who abruptly resigns and disappears. Are the notes asking for help real or is it a game? Hunter Grant, ex-army and with a pragmatic view of justice, reluctantly agrees to help find the missing woman. A high-powered lawyer arrives form the US, and shortly after his meeting with Hunter and Dao a "cease and desist" letter arrives from the Cayman Islands.
Inspector Bakker - a woman, who in Hunter's words "looks as if she would be useful in a brawl, provided she was on your side" - takes instant exception to his involvement and threatens to arrest him for interfering in an investigation. Dao sets out alone on a dangerous mission, driven by a compulsive need to find out what has happened to the girl who wrote the notes, and Hunter looks death in the face when he decides to risk everything to put an end to the Darknet forces that threaten their lives.