Date: December 5, 1928. Place: San Francisco; the office of detectives Samuel Spade and Miles Archer. Private dick Sam Spade is at his desk when his secretary Effie Perine knocks to announce a new customer: Miss Wonderly.
Miss Wonderly is a knockout. The tall, slender, blue-eyed redhead, dressed in two shades of blue (to bring out her eyes, of course), has come to ask Spade to help her find her sister Corinne, who appears to have run away from New York to San Francisco with a man named Floyd Thursby.
The door of the office opens. Miss Wonderly puts a startled hand on her mouth, but it is only Miles Archer, Spade's partner.
Reassured that she is in no danger, Miss Wonderly continues her story, explaining that she has a meeting scheduled with Thursby that night at 8 o'clock.
Spade agrees to have them followed, and Miss Wonderly offers Spade and Archer $200 for their services. Fearing for her sister's life, Miss Wonderly warns the two detectives that Thursby is dangerous and known to be violent.