What are the motifs in Four to Score by Janet Evanovich?

Danger is a recurring idea in this novel as Stephanie Plum is a bounty hunter, and the nature of her job causes her to place herself in danger. At first, Stephanie's job seems easy. Stephanie begins by simply interviewing people. However, it quickly proves to be a little more complicated than this when the people that Stephanie has visited turn up with morbid wounds or dead. Later, Stephanie goes in search of one of her witnesses and finds herself caught by the real bad guys, people she had assumed were friends. One of them pulls a gun on Stephanie and threatens to kill her until Morelli shows up just in time to save the day.