The best-selling author arrived in Guinea-Bissau from the Portuguese capital Lisbon just after the army chief-of-staff, General Tagme Na Waie, was assassinated on Sunday.
He was trying to sleep in his hotel room in the early hours of Monday morning when he heard an explosion.
It was the roof of the presidential villa collapsing as soldiers launched an apparent tit-for-tat attack on veteran ruler Joao Bernardo Vieira.
Later, in an interview with the BBC, the author explained what had happened.
"They went to his villa, threw a bomb through the window which hurt him, but didn’t kill him. The roof came down, that hurt him but didn’t kill him either. He struggled out of the rubble and was promptly shot. This, however, still didn’t kill him. They then took him to his mother-in-law’s house…
(…if they’d left this part out )…and chopped him to bits with machetes."
Mr Forsyth, who had dinner with the forensic pathologist investigating the assassination on Monday evening, has a theory why this happened.
"Basically these two men absolutely loathed each other," he said. "The president was a very violent man and the chief-of-staff was a pretty violent man too. We are not talking about two Mother Theresas here".
Knowing Mr. Forsyth, I imagine those lines are already copyrighted for use in his next novel.