The footage shows the terrier Max, voiced by Patton Oswalt, being taken to the vet by his owner (Ellie Kemper) due to the stress of protecting her toddler son Liam.
Kevin Hart’s rabbit Snowball later tells Max, “The baby is leaving the nest,” as Liam heads off to preschool for the first time. Harrison Ford, making his animated-film debut as the Welsh Sheepdog Rooster, pushes Max to deal with his fears.
“The first step of not being afraid is acting like you’re not afraid,” Rooster declares.
The voice cast includes returnees Chloe the tabby cat (Lake Bell) and Gidget the Pomeranian (Jenny Slate), as well as newcomer Daisy the Shih Tzu (Tiffany Haddish). Oswalt replaces original star Louis C.K. as Max.