The Templeton brothers — Tim (James Marsden) and his Boss Baby little bro Ted (Alec Baldwin) — have become adults and drifted away from each other. Tim is now married and the stay-at-home dad of two daughters, Tabitha (Ariana Greenblatt) and baby Tina (Amy Sedaris). Ted is a hedge fund CEO who doesn't have time for his brother or his nieces.

But when it turns out Tina is a boss baby with a cutting-edge approach and a can-do attitude, she brings them together again to inspire a new family business.