Values Dissonance: In one of the endings for Your Code Name is Jonah (aka Spy Trap), you decide to quit your job as a spy saying "I want to study whales, not exploit them." Your boss responds by saying that "It's not done! It's unpatriotic". He eventually accepts your resignation but then concludes his fuming with the bottom line: "But don't think for a moment that being a spy is immoral. After all, we are the defenders of freedom." Today, it would be hard to not feel embarrassed for him. It must be remembered that in this 1979 book, you are in the role of an American government agent versus the Russians.
The premise of one of the books, Tattoo of Death involves mature themes such as human trafficking. One ending even had an illustration showing your character having his chest blown through by a laser beam.