“What do all cocky men do?” If that isn’t a loaded question, I don’t know what is. What I do know is “I, Witness” is chock full of red herrings, suspects, and a whodunit fit for superb mystery novel. When Eva Whitfield (Brianna Brown), Castle’s (Nathan Fillion) former classmate, asks him to find out whether her husband Cole (Ivan Sergei) is cheating, he gets more than he bargained for. Turns out his new client ends up dead! Queue dramatic music.