Tim and his wife, Carol (Eva Longoria), the breadwinner of the family, live in the suburbs with their super-smart 7-year-old daughter Tabitha (Ariana Greenblatt, Avengers: Infinity War), and adorable new infant Tina (Amy Sedaris, BoJack Horseman). Tabitha, who’s at the top her class at the prestigious Acorn Center for Advanced Childhood, idolises her Uncle Ted and wants to become like him, but Tim, still in touch with his overactive youthful imagination, worries that she's working too hard and is missing out on a normal childhood.

When baby Tina reveals that she's – ta-dal – a top secret agent for BabyCorp on a mission to uncover the dark secrets behind Tabitha's school and its mysterious founder, Dr. Erwin Armstrong (Jeff Goldblum), it will reunite the brothers in unexpected ways, lead them to re-evaluate the meaning of family and discover what truly matters.

Lisa Kudrow and Jimmy Kimmel also reprise their roles as Ted and Tim's parents.