Math genius Charlie Eppes (David Krumholtz) applies advanced numbers theories in unusual ways to help his FBI agent brother, Don (Rob Morrow), solve his toughest cases in this police drama inspired by actual crimes that features real mathematical concepts. In the fifth season, the brothers match wits against a new crop of criminals. Judd Hirsch co-stars as their curmudgeonly dad, and Peter MacNicol plays Charlie's mathematical mentor.