Radical Advantage

A suspicious husband has hired PI Bianca Steele to due surveillance on his wife who he suspects of cheating on him. The husband provides Bianca with all the background details and even provides Bianca with a video of his wife with another woman from before they were married. Bianca follows the wife and has narrowed down who she is having the potential affair with. She has set up a surveillance location and waits for the cheating wife to show up.
Bianca has brought along a video recorder to capture the wife in the act. She realizes that the apartment she has to video is on the third floor and is afraid of heights. To her good fortune she spies a young girl named Brooke, climbing down the fire escape and convince her to do the videography for her. The girl says she'll do it for $200. The girl she has hired spends over an hour on the fire escape videoing the action from the apartment.
When Brooke returns Bianca asks if she got the incriminating evidence. The girl assures her she has the goods but says that it's not what Bianca expected. Getting in Bianca's car they Brooke goes back to Bianca's to watch the video. The video is a shock to Bianca and realized Brooke wasn't exaggerating about what she found. The video of the cheating wife is not only shocking, but Bianca also finds it somewhat stimulating.
And there in front of her is Brooke smiling like the Cheshire Cat.