Tom Clancy published Rainbow Six in 1998 as his second novel centering on John Clark, and it follows the hero as he organizes a multinational counter-terrorism division within the Central Intelligence Agency called Rainbow.
The book (which also inspired a popular series of video games) centers on the attempt to stop a bioweapon attack that would see the entire world infected by a deadly virus – though it’s unclear exactly how close a movie adaptation would stick to the source material, especially given that Tom Clancy’s Without Remorse greatly deviates from the text with which it shares a name.