Wilbur Post and his wife Carol move into a beautiful new home. When Wilbur takes a look in his new barn, he finds that the former owner left his horse behind. This horse is no ordinary horse . . . he can talk, but only to Wilbur, which leads to all sorts of misadventures for Wilbur and his trouble-making sidekick Mister Ed.
Ed discovers that some spies are using the park to drop secret messages. When Wilbur then finds some microfilm, his imagination starts to fly.
A neighbor who happens to be a builder needs an architect. Ed comes up with an idea that go-go music might just help Wilbur get that job.
The Chief of the Secret Intelligence Agency calls on Wilbur to find a tiny secret radio that has disappeared. Ed finds the only clue to it.
When Ed and Wilbur recover a mini radio for the Secret Intelligence Agency, the two are threatened by spies.
Carol attemps to publish Ed's memoirs.
The SIA (Secret Intelligence Agency) once again enlists Wilbur to try and find out who exactly has been stealing papers from the agency. In order to help solve the case, Mister Ed needs to speak with a monkey, so he uses a zebra as a translator.
Ed answers a hard question regarding chess on a radio game show and ends up winning Wilbur a new color TV set.
Carol offers to look after a friends cat, but Wilbur ends up doing most of the work, making him busy. Ed then starts then feeling neglected.
Ed is opposed to a gift that Wilbur received. It is a bearskin rug and Wilbur refuses to get rid of it until is gets up to chase him.
Ed begs Wilbur to find him a Justice of the Peace so that Ed can marry his favorite filly.
Ed decides that he only wants to be ridden bareback and does not want Wilbur to use a saddle on him, so Wilbur then goes and rents a motorcycle.
Ed discovers that he's part Indian steed and refuses association with a parrot descended from General Custer's parrot.
Wilbur pleads with Ed to stick to being a horse, especially when Ed wants to go to college to become a Doctor.
