<p>Colombian drug lords, bored with Uncle Sam's hectoring, assassinate the head of the FBI. The message is clear: Bug off! </p> <p>At what point do these druggies threaten national security? When can a nation act against its enemies? These are questions Jack Ryan must answer because someone has quietly stepped over the line. </p> <p>Does anyone know who the real enemy is? How much action is too much? Which lines have been crossed? Ryan and his "dark side", a shadowy field officer known only as Mr. Clark, are charged with finding out. They expect danger from without... but the danger from within may be the greatest of all.</p>