Without Remorse

Without Remorse is a novel by Tom Clancy set in 1970, in the middle of the Vietnam War. John Kelly (former Navy SEAL) is tired of war, and resigns from the United States Navy to run an underwater demolition service. From this point on, his life is a series of tragedies, where the final crisis results in Kelly getting critically wounded, and his girlfriend killed by a drug selling operation.

From this point on, Kelly takes charge, both in a private war against the drug business which killed the girl he loved, and in a military operation to free dozens of secretly held POWs, where he is operating as John Clark, believed to be CIA.

The main purpose of this book appears to provide a setting to build the character of John Clark, as a highly intelligent, strong and resourceful persona, with a sense of personal justice that transcends mere legalities.

It is a prequel to the Jack Ryan books and even includes Jack Ryan as a young adult about to start college. Jack's father plays a prominent supporting role.