Oct 1942. WWII. In the secret annex where Anne Frank is in hiding from the Nazis with her family and close friends the Van Daan family, the toilet is blocked and her father, Otto, is forced to try and unblock it with a stick. When he fails, they have to resort to using jam jars until it is mended. Their helpers in the offices downstairs call a plumber, and the family are terrified that he will need to come up to the annex and they will be discovered. Fortunately, it is finally sorted from downstairs and all is well.

Anne finds Mrs Van Daan increasingly hard to bear, as she orders her around and criticises her in a way that her liberal parents never do. She also finds Peter Van Daan frustratingly dim, and never misses an opportunity to tell him so. But overall they are getting used to their incarceration, and the strict rules of daily quiet by which they must live. Otto oversees their school studies and everyone has their routine tasks to perform. Only at night when the bomb raids start is Anne so scared that she runs into her parents' room for comfort.

Anne invites Miep and her husband Jan to come to dinner in the annex and to stay overnight in her room, while she and Margot camp in their parents' room, and Miep agrees. Anne is thrilled and draws up a special menu in their honour, which Mrs Van Daan cooks for them. But Miep brings the bad news, which she tells only the Franks, that the Van Daans' apartment has been ransacked by the Nazis and all their property confiscated. When Mrs Van Daan asks Miep to bring her some more of her things, it is Anne who covers the difficult moment with a toast to the helpers.

Anne is having a birthday party. She is blowing out the candles on her magnificent chocolate cake, surrounded by friends. Suddenly she wakes up and remembers she is in the annexe, and her 14th birthday will be a much more modest affair. Her family give her whatever they can, but the only present that really excites her is the bar of chocolate she is given.

Anne is growing into a young woman and is amazed by the changes happening to her body and emotions. Her periods have started and she is becoming aware of her sexuality. She has even started to look differently at Peter, especially when he passes her on the stairs, wearing just a towel. Otto measures Anne and Margot against the wall and finds that Anne has grown three inches in the last year.

The families are growing out of their clothes and don't have the money to replace them. In fact, the Van Daans have little money left and row furiously about whether they should sell Mrs Van Daan's fur coat. When Anne walks in on their argument, Mrs Van Daan turns on her and Anne goes up to the attic to sulk.

When Peter comes up to the attic she tells him that she sees him differently now and apologises for having teased him in the past. She asks him if he finds Margot attractive and he says he's never noticed. She invites herself to accompany him down to the warehouse to collect the potatoes.