In the tradition of Sherlock Holmes and Dr. Watson—or Law & Order: SVU's Benson and Stabler—before them, O'Rourke and Mendoza are your classic detective duo. They banter, they say things like "Yowza!" to each other, they slide important documents in manila folders across metal tables. (Editor's note: We're fairly confident Sherlock Holmes never said "Yowza!")
However, unlike their storied predecessors, who typically have complementary strengths and weaknesses, these two may as well be the same character. While Joe Mendoza gives Grace his business card, we actually never even learn Detective O'Rourke's first name—we're assuming it's not Beto.
The detectives mostly serve as a way to move the story forward and reveal new information to Grace, shattering her world a little more with every single interaction. Just in case there are any skeptics, here's a rundown of what Grace learns each time O'Rourke and Mendoza appear in the book:
All of those revelations send Grace into various spirals of rage, shock, and/or grief, so although O'Rourke and Mendoza are bit players in the novel, they make the most of their time in the spotlight.