The Judas Conspiracy

In January 1971, Colin, an officer from British Special Branch recruits eighteen-year-old Sam Nathan to infiltrate a group of student extremists who they believe are planning a terrorist attack in Sam's home city of Glasgow, Scotland.
Sam foils the plot, narrowly escaping being murdered by one of the gang named Max Jordan. In gratitude for his efforts, he is invited to the prestigious event that the gang tried to ravage. During the celebrations, Sam is introduced to a statesman who inadvertently reveals to him highly classified intelligence. This information leads Sam to understand the true motive behind the assassination of President John F. Kennedy.
The details are so horrifying that he cannot reveal them for fear of ridicule, or worse, for the fact he might be believed. Concerned that making his knowledge public might endanger his life, Sam keeps these facts to himself, intending never to disclose them.
However, an episode in 2007 changes his mind. Sam finally decides to write about his adolescent experiences, his actions unwittingly threatening to destroy global alliances and bring him face to face with his nemesis who has waited half a lifetime to exact his revenge.