During a thunderstorm, a carrier pigeon flies into the Simpsons' house. After discovering that its wing is injured, Lisa instructs Bart to take care of it, because she has a phobia of pigeons. Bart agrees to take it in, and nurses it back to health over several weeks. He tries to release the bird back into the wild, but he and the pigeon (nicknamed "Ray") have became too close, and so Bart chooses to keep the bird as a pet.
After seeing an advertisement for a video about the role for carrier pigeons in the Second World War, Bart and Homer plan to train Ray to carry messages, while Marge is teaching Lisa that it is okay to be afraid of a single animal while caring about all the others, as she is scared of possums herself.
After training Ray to deliver messages, Bart and Homer use his ability for several pranks, such as Bart sending Mrs. Krabappel a message stating "Who Cares?" during a lesson and Homer sending Mr. Burns a message suggesting he should "do a ballet dance with no clothes on". Bart also sends Milhouse a message to become friends with him again, as they had a fight earlier over a toy Milhouse had broken because he thought it was a transformer.
Moe comes by the house, suggesting that Ray might become a racing pigeon. As he is discussing it with Homer and Bart, however, Santa's Little Helper eats Ray, despite Homer's attempt to rescue him. Overcome with grief, the family holds a funeral for Ray and Bart becomes resentful of Santa's Little Helper.
Marge and Homer take Bart to see Dr. Thurston, a psychologist. She suggests to Bart that he should forgive Santa's Little Helper, as he is the smarter of the two and knows that dogs do not have the brain capacity to know that it is wrong to kill small birds. Bart still cannot forgive, so the family plan to take him to live on a farm upstate, Ostrich World. Bart shares parting words with Santa's Little Helper, telling him to never kill a bird again.
As the family is about to leave, Homer releases an ostrich and it starts attacking the family. Bart calls for Santa's Little Helper to help, but he is confused, since Bart told him earlier it was wrong to hurt birds. Bart ends up clobbering the bird with some nearby tools and eventually strangles it, forgives Santa's Little Helper, and the family leaves happily with the unconscious Ostrich on the roof, saying that they don't have to buy dinner, and Lisa says that they do for her. As they are driving, though, the bird wakes up, breaks through the roof, and starts strangling Homer with its foot. The final scene of the episode depicts the car swerving down the road as Homer tries to gain control as he is strangled and Lisa rolls her eyes.