Eamon Martini: A 7-Book Political Action Thriller Series by P.M. Heron - Kindle Edition

From Book 1:

The US president's grandson has been kidnapped. Six Secret Service agents have disappeared, presumed dead.

A video shows the boy with a machete to his throat. He is about to pay for the actions of others, in a world he does not yet understand, unless POTUS meets one demand:

ASSASSINATE THE BRITISH PRIME MINISTER.

POTUS calls the only person he can trust: Eamon Martini, ex-Marine and CIA black-ops specialist.

Long before enlisting, Martini had become hardened to violence. He knew of nothing else. His mother, Queen of New York, was the head of one of New York's five families. His father, Damien Cleary Jnr., was a Belfast-born commander of the Irish Republican Movement.

Martini had angered British Intelligence once before. Now they know he's back across the Atlantic, and have sent their best assassin to put him down once and for all.

Will they be able to stop him, or will he find a way to save the boy and prevent a diplomatic disaster?