Returns: Friday, April 4, at 10 pm/ET (CBS) Number of new episodes: 6

Where we left off: Overcoming his math block, Charlie (David Krumholtz) helped his FBI agent bro, Don (Rob Morrow), catch a rapist cop. What's next: After several recent brushes with danger, Charlie undergoes FBI training at Quantico. "There are things he likes about it and things that are tough for him," exec producer Cheryl Heuton says. A case about academic freedom versus national security causes a sharp split between the Eppes brothers. Feds in love? Don is assigned to protect his old girlfriend, ADA Robin Brooks (Michelle Nolden, back for three episodes); Amita (Navi Rawat) introduces Charlie to her folks; and things between Megan (Diane Farr) and Larry (Peter MacNicol) warm up. Watch full episodes | Photos | More Returning Favorites coverage