Persuader by Lee Child (by Liam)

Jack Reacher, is a ex-MP who sets up an undercover operation with the FBI to rescue an agent investigating Zachary Beck, a reclusive tycoon believed to be a kingpin in the drug trade. It begins with Reacher rescues Beck's son from a staged kidnapping in order to get close to his father and discovers a connection between Beck and Quinn, a former army intelligence officer who tried to sell blueprints of a secret weapon to Iraq but was murdered before he could pull it off. Or so Reacher thinks, until he spots Quinn in the crowd at a concert in Boston. Now Jack has to find out the truth between these two men without being discovered himself.