What happened in the Annex on March 24, 1943, in "The Diary of Anne Frank"?
On the night of March 24, 1943, Anne and her family were, in her words, sitting quietly when Peter whispered something into Mr. Frank's ear. Anne caught only the words "a barrel falling over in the warehouse" and "somebody fiddling with the door." They were afraid that they had been discovered. Everyone immediately got very quiet and waited.
However, often at night they would leave the annex and go into the office to listen to the radio. That night, some of them had been doing just that and had left the office chairs in a circle around the radio, which would look very suspicious in the morning. They also worried that if there had been any intruders, they might have left the door open, which would cause an investigation if it were discovered by the air raid warden.
So Mr. Frank, Mr. van Daan, and Peter went downstairs to check things out. They didn't find anything, but everyone remained very quiet for the rest of the night.