It starts with Paddington sleeping in his bedroom. There is a loud noise of hammering in the backyard. He sees a man building what he thought was a shed. He then runs downstairs to tell Johnathan and Mrs. Bird. They said it was a sauna for Mr. Brown's Birthday. Paddington offers to test it but Mrs. Bird scolds him saying Mr. Brown will try it first. Mr. Curry yells "Bear!" and Paddington falls down from a box. Paddington tells Mr. Curry that it was a sauna for Mr. Brown's Birthday. Paddington says he should try it some time. Mr. Curry then takes advantage of Paddington saying he should try it now.
Then Mr. Curry goes to his house with Paddington to find his towel. Mr. Curry while looking for his towel says "I musn't forget to lock up" so Paddington gets an idea to lock up the sauna. He places the lock on the door of the sauna. Then he hears a muffled noise from the saunua. Then Paddington sees Mr. Currys clothes thrown across the yard and realizes what he did. Mr. Curry demands to be let out of the sauna. Paddington set the lock code as his 2nd birthday which is December 25th. He tried his first birthday June 25th. Paddington then climbs on the roof and pours cold water down the smoke stack. Then even more steam was in the sauna. He then called the lock company which he brought the lock from. Paddington tells him he forgot the combination and says that he should bring the lock down to the shop. Paddington explains that it was already locked to something. So he says he'll call back if he remembers. Then the phone rings and Johnathan picks up. The lock man tells him to tell Paddington that it was his Birthday. Then Mr. Brown arrives and Mrs. Bird keeps him talking. Then Johnathan tells Paddington the code and he opens the lock. Mr. Curry walks out and Paddington pours the bucket of cold water on him. Mr. Curry then leaves through the broken plank in the fence. Mr. Brown asks his family and Mr. Curry to join him in the sauna, but Mr. Curry snaps "He has half a mind to report that thing."