While his family welcomes his newborn brother, the 7-year-old Tim is disgruntled that his new brother is stealing all the attention away from him. But when Tim learns of the nefarious scheme of the CEO of Puppy Co, he teams up with his baby brother to put a stop to it.
After having grown up and drifted apart, Theodore and Tim Templeton team up with a new boss baby, as they work together to thwart the plot of an evil scientist.