Mary Shannon is the tough talking U.S. Marshal on In Plain Sight. But don't let that fool you, she really is that tough. She can hang with the best of them...but very few can hang with her. She doesn't believe in holding witnesses hands but she's one of the best at her job. Mary is constantly annoyed by her family, but she loves them and often bails them out of their messes...even when they don't appreciate it.
Mary's partner and best friend is fellow Marshal, Marshall. In fact, she had at one time called him her only friend. Even though there's times that Marshall's incessant droning on of useless trivia gets to her, he always has her back and she has his as well. They are completely polar opposites of one another but somehow it's the perfect partnership.
Mary tells it like it is...never backs down...she'll tell you exactly what she's thinking...and she doesn't suffer fools. Mary loves her job...she'd much rather be at work then deal with her family. Dr. Shelly Finkel, the department psychiatrist had followed Mary around after Mary returned to work following her kidnapping ordeal. Her final assessment was that she had never met anyone under the amount of stress Mary is under, but she also recognizes that Mary's job is about the only avenue she has to vent off that stress. And her job is about the only thing keeping her sane.