Plot
In 1980s Manhattan, Dog lives alone. While watching TV, he notices an advertisement for a robot friend and immediately calls to order it. Dog receives Robot in the mail sometime later and assembles him. The two become instant friends as Dog takes Robot out to explore Manhattan. They make their way to Central Park where they involve themselves in a host of activities, notably roller skating to Earth, Wind & Fire's "September". Over the course of the summer, the two become inseparable friends.
Near the end of summer, Dog takes Robot to the beach. After a long day of playing in the water, the pair falls asleep on the beach. Upon waking up well after all the other visitors have left, the pair realize that the water has caused Robot to rust in place. Unable to move Robot, a disheartened Dog is forced to head home for the night. Dog returns to the beach the following day to discover that the beach has been closed until June 1 the following year, with a large barbed wire fence constructed which prevents him from reaching Robot. After being denied access to the beach by the city, Dog tries to illegally break past the fence. However, he is caught by police and is arrested. Afterwards, a disheartened Dog relents to wait until June 1 to go back and rescue Robot, placing a note on his refrigerator as a constant reminder.
Sometime later, a trio of rabbits comes across Robot on the beach. They give him STP oil that fixes him and allows him to leave the beach. He returns to Dog's apartment only for it to be revealed that this was all a fantasy of Robot's. In reality, the rabbits chop off one of Robot's legs and remove one of its toes to fix their broken boat. They discard the leg and leave Robot alone on the beach once again. Meanwhile, Dog spends Halloween alone.
Winter arrives as snow begins to fall across the city and the beach. After having a dream of escaping the snow and returning home to find Dog having replaced him with a new robot, Robot becomes frozen in ice. Meanwhile, Dog goes to the Catskills to meet new friends after seeing a newspaper advertisement. This only leads to him breaking his arm in a sledding accident following a conflict with a pair of anteaters. As winter continues, Robot has another dream of returning home through a world inspired by The Wizard of Oz . Dog meets a magical snowman who leads him to a bowling alley. Dog bowls poorly but finds a new friend in the snowman; only for this to be revealed as a dream.
Following the end of winter, Robot befriends a bird who winds up building a nest next to his arm. The bird lays three eggs that hatch, the youngest child instantly bonding with Robot. The bird's three children grow over a period of time with the youngest remaining the most attached to Robot. When the time comes for the birds to leave, the youngest is the most hesitant to leave Robot; but they ultimately relent and follow after their family following encouragement from Robot. Dog, meanwhile, finds a new friend in Duck during a kite outing and the pair go fishing sometime later. Duck suddenly moves to Europe afterwards, leaving Dog alone yet again.
A monkey sneaks onto the beach and happens upon a buried Robot with help from his metal detector. The monkey takes Robot to a junkyard to sell him. The alligator owner and his son promptly chuck Robot into the pile, where he is promptly broken into different pieces and shuts off. When June 1 finally arrives soon after, Dog returns to the beach but is only able to find Robot's discarded severed leg. He is kicked off the beach after spending the whole day digging. A saddened Dog spends the night laying in bed with Robot's leg.
A raccoon named Rascal visits the junkyard sometime later and discovers Robot's head and remaining limbs. He takes the parts home and, following his interest in building robots on his own, rebuilds Robot with a giant radio as a new body. Robot turns back on, seemingly with no memory of his time with Dog. Meanwhile, Dog goes to a robot store and buys a new robot named Tin. Over the course of the summer, Robot and Rascal form a close friendship as do Dog and Tin. Dog and Tin go to the beach and, learning from his past mistakes, Dog coats Tin with oil spray and keeps him out of the water.
Later, while getting ketchup for a rooftop lunch with Rascal, Robot looks out and sees Dog and Tin walking down the sidewalk. Robot regains all his memories of his time with Dog. Racing out of the building and down the street, Robot manages to catch Dog and reunite with him. The sudden appearance of Rascal reveals that the reunion was yet another fantasy of Robot's. Instead of chasing after Dog, Robot uses his radio body to play "September". Dog hears the song echo down and the pair (unbeknownst to Dog) dance together to the song for the final time. Dog sees a reflection of Robot in a window and Robot promptly hides from view. Robot contemplates revealing himself. However, realizing that he and Dog have found meaningful new relationships following their separation, Robot continues to hide and lets Dog continue on with Tin. Tin notices Dog's sadness and promptly cheers him up as the two danced down the street side by side. Robot then happily returns to Rascal and the two proceed to dance together on the roof.
