It is Dug's birthday and Dug wishes that it will be the happiest day of his life. Suddenly, a huge prehistoric female bird runs over him and Alpha, Beta and Gamma run into Dug. Irritated with Dug getting in their way, they come up with "special missions" for Dug to help capture the bird. However, these are just ploys to keep Dug out of their way. Alpha assigns Dug to watch a large rock and make sure it doesn't move, because it is "the bird's favorite rock." Dug accidentally causes a pebble to roll down an incline and topple the large boulder, which nearly crushes Alpha, Beta and Gamma. He is then told to sit and wait in "the bird's favorite hole." After the three dogs leave him there, it turns out to have quicksand in it. Dug falls through it and ends up falling on top of the three dogs right as they are stalking the bird.
Dug is then assigned to sit on a rock. Dug jumps onto a rock, causing Alpha, Beta and Gamma to fall from the rock that Dug had just occupied with them and the three of them fall, including the rock. Numerous scenes follow of Alpha, Beta and Gamma being caught or captured by traps intended for the bird, due to the actions of Dug as a result of commands given to him by Alpha. The trio is scooped up in a net and shot with darts, one of which hits Beta, causing him to pass out. Dug is then seen running on top of a pile of rocks as Alpha, Beta and Gamma chase after him. The rocks fall down, causing Alpha, Beta and Gamma to fall down into the canyon below, screaming as they fall.
In anger, Alpha contacts Charles Muntz in his airship to report that Dug has caused them "to not capture the bird" and that he is a "bad dog." Dug, dismayed, suddenly sees Muntz's Spirit of Adventure blimp. Fearful of Muntz and emotionally hurt, Dug runs off. Gamma and Beta talk to Dug by radio and comment on how he is "gonna get it now"; Beta then sarcastically wishes Dug a happy birthday. Sad and lonely, Dug runs off into a mist-laden rocky area. He sees a rock that resembles a turtle and then one that looks like a man. When he hears a voice, he asks if the man is OK. Dug then realizes that he has received his birthday wish: a new master (Carl). The clouds clear, the sun comes out and Dug sits proudly on a flat rock. Russell notices him and briefly thinks Dug is a rock. After the credits, Dug says "Hi there!" to Carl and Russell; the short ends with Carl and Russell gasping in shock.
Jonas Rivera, Up producer, revealed Dug's Special Mission "is a little bit of the backstory of what Dug was actually doing out there on this mysterious mission when we meet him."
There are a few inconsistencies in this short. The short implies that Dug was chased out of retaliation by Alpha and his gang prior to Dug meeting Carl and Russell, while in the movie, he was still under the impression that Alpha sent him on a "special mission." Beta and Gamma even say it themselves. Also, Alpha's voice is already faulty and comically high-pitched, yet in the movie, when the pack is first introduced, Beta and Gamma express surprise at Alpha's faulty voice, as if he had been speaking with his real voice until then.