Ed Plum is the inexperienced, youthful lawyer Westing chooses to handle his will. Judge Ford is surprised that someone that rough would be chosen for the job. Plum has an annoying habit of clearing his throat before he reads each part of the will, he's a little clumsy/bumbling, and he freaks out at the end of the game because of all the craziness —what with dead bodies and confessions and all—and ends up jumping ship.
At one point, Grace and Mr. Hoo think their clues point to his name, and he's the murderer, but nothing really comes of that. He's also interested in Angela, mostly for her looks... but nothing really comes of that either.