Dead if you don't / Peter James.

A parent's worst nightmare is Grace's deadliest case...Kipp Brown, successful businessman and compulsive gambler, is having the worst run of luck of his life. He's beginning to lose big style. However, taking his teenage son, Mungo, to their club's big Saturday afternoon football match should have given him a welcome respite, if only for a few hours. But it' at the stadium where his nightmare begins. Within minutes of arriving at the game, Kipp bumps into a client. He takes his eye off Mungo for a few moments, and in that time, the boy is gone. Then he gets the terrifying message that someone has his child, and to get him back alive, Kipp will have to pay. Defying instruction not to contact the police, Kipp reluctantly does just that, and Detective Superintendent Roy Grace is brought into investigate. At first it seems a straightforward case of kidnap. But rapidly Grace finds himself entering a dark, criminal underbelly of the city, where the rules are different and nothing is what it seems.