First, as the Nazis tightened their grip on the Jews in Amsterdam, the Frank family decided to go into hiding in an annex. During their time in hiding, they had to rely on the kindness of a few people to bring them food and supplies. Anne wrote in her diary throughout this period. Then, unfortunately, they were betrayed and arrested. They were then sent to different concentration camps, which was a major turning point in their story. Otto Frank's survival was the only glimmer of hope in an otherwise very dark story.
The Frank family, being Jewish, had to flee the Nazis. So, they hid in a secret annex. This was a major event. Their time in hiding was filled with secrecy and fear. However, the most crucial and tragic event was when they were found and deported to concentration camps. Only Otto Frank survived in the end.
The key event was going into hiding. The Frank family hid in the annex. Then there was the discovery of their hiding place. After that, they were sent to concentration camps.