The fifty million hijack - Allan Cecil

Ann Seaton is a highly trained security guard, transferred from a tough New York police precinct.
Under cover, she accompanies an American millionaire industrialist, whose life is threatened, on board a luxury yacht where a meeting with three other millionaires is to take place.
This has not gone unnoticed by an international group of terrorists whose aim is to take the yacht, extort a ransom of fifty million dollars, and then cold-bloodedly sink the boat with all its occupants.
Single-handedly, Ann Seaton somehow copes with this seemingly impossible situation.