Brigid O'Shaughnessy (Mary Astor)’s Timeline and Summary

Brigid, as Ms. Wonderly, goes to Spade, telling him her sister is missing and Floyd Thursby is to blame.
After Thursby is shot, Brigid tells Spade her name is Ms. O'Shaughnessy and she is looking for something.
She tells Spade that "the fat man" is after her. He killed Thursby, and he's after her next.
Brigid and Spade begin a romantic relationship.
The day after Spade meets Joel Cairo, he brings Brigid and Cairo together to talk about the Falcon, and Brigid and Cairo fight.
Later, Brigid is intimidated by Gutman, Cairo, and Wilmer into giving them the Falcon, but she doesn't have it. Spade does.
Finally, everyone is brought together and the Falcon is revealed to be a fake.
Spade realizes that Brigid actually killed his partner, and he turns Brigid in to the police.
She'll go jail for a long time, and may hang.