Tim Templeton and his little brother Ted, the famous Boss Baby, have become adults, they live on their own, Tim has become a tidy family man and Ted is the head of a large speculative fund. But the arrival of a new Boss Baby, with a whole new approach and innovative strategy, is about to bring the enemy brothers together ... and inspire a new model in family affairs. Tim and his wife Carole live in the suburbs where he takes care of the household while she boils the pot. They have two children: Tabitha, a remarkably intelligent 7-year-old girl, and Tina, their adorable newborn. Tabitha, first in her class at a school for the gifted, adores her uncle Ted and dreams of following in his footsteps, which worries Tim very much, who fears that she will miss out on her childhood by working so hard.