It is Mr. and Mrs. Brown's anniversary and Paddington's noticed Mr. Brown is behaving rather oddly. Mr. Brown is pretending he does not remember so his gift will be that much more of a surprise. But when Paddington is sent to collect the gift, a piano, it will be a miracle if the whole town does not find out about it.

Mr. Curry thinks Paddington's made him an April Fool, so he retaliates by sending Paddington on a fool's errand. Poor Paddington does not even know what April Fool's is. Aunt Lucy always taught him it was rude to play tricks on people. But in this case, Paddington's honesty turns out to be the best trick of all.