The show (which is set in Washington, D.C.) centers on the misadventures of boy genius T.J. Henderson (Tahj Mowry), who at the age of 10 moves from elementary school and gets transferred to Piedmont High School, where ...展开he ends up becoming a high school sophomore with 15-year-olds as his classmates. He must adjust to the life with older but not necessarily wiser high school teenagers — his brother Marcus (Jason Weaver) and Marcus's best friend Mo (Omar Gooding). He often deals with the usual missteps of trying to fit in as a kid genius, while being a small kid in high school.
Older brother Marcus, the suave and underachieving middle child, also deals with teenage problems, such as finding a date, and doing homework (though he sometimes tries to get T.J. to do his homework for him). Their father Floyd (John Marshall Jones), a single father who owns his own roofing business, deals with the problems of raising his three kids, Yvette, Marcus and T.J. since his wife's death. Floyd's only daughter, and Marcus and T.J.'s older sister Yvette (Essence Atkins), is (usually) the level-headed one of the family and is the typical overachieving student.
Episodes deal with T.J.'s attempts to fit in high school, as well as the contrast between his smarts and his brother's underachieving nature.