Jack Higgins - Sean Dillon Series: Books 5-6: Drink with the Devil, The President's Daughter 2016

DRINK WITH THE DEVIL A fortune in stolen British gold lies shipwrecked at the bottom of the Irish Sea. And history's deadliest treasure hunt is on. Irish militant Michael Ryan wants to finance war in his homeland--and a sinister pact with the New York Mafia will make his dreams a savage reality. Former IRA enforcer Sean Dillon now works for the British government. His mission: retrieve the gold by any means necessary--and finish Ryan's bloody plot before it gets off the ground. Two deadly men are locked in a furious race, with millions of dollars--and lives--hanging in the balance....

THE PRESIDENT'S DAUGHTER In 1969, Jake Cazalet saved the life of a Frenchwoman in Vietnam, and a brief, passionate affair ensued. Years later in Paris, he was introduced to another beautiful young woman--his daughter. For many reasons, their relationship remained a secret. Now Jake Cazalet is president of the United States. Somehow, someone has discovered the truth about his daughter, and she is seized by a vicious extremist group. If the president does not comply with the kidnapper's demands--or uses any of America's security agencies to track them down--hey will execute her. He has ten days to decide. Desperate, he turns to British operative Sean Dillon and FBI agent Blake Johnson. And if these two men cannot find his daughter, the president will have to make the most momentous decision of all....