A.P. Bio is back in session! Season 4 of the critically-acclaimed comedy series returns to the halls of Whitlock High for more laughs and misadventures with Advanced Biology teach Jack Griffin (Glenn Howerton) and his lovable roomful of honor roll students. Patton Oswalt is back as the adorable Principal Durbin alongside fan-favorite Paula Pell as Durbin's secretary Helen, plus Mary Sohn, Lyric Lewis and Jean Villepique as the hilarious teaching trio of Mary, Stef and Michelle. Get ready for an hysterical season featuring new schemes, new school uniforms, Jack's estranged dad (guest star Bruce Campbell) and much more.