Struggling with Relationships

The divorced mother, Julie, and her daughter Paige,  are both out for Summer Break. Julie is a college professor and Paige will be an incoming freshman in the fall. During the summer Paige's best friend, Chelsea has been a constant presence in Julie's house, as Chelsea and her daughter are very close. One afternoon Julie hears a commotion going on in her living room, and when she goes to investigate, she finds Paige and Chelsea wrestling around on the floor.
As Julie watches she learns the point of the contest is to see who can spank the other's bottom the most and the hardest.  Julie allows the shenanigans to continue because she is fascinated but is forced to stop it so Paige can get packed for a trip with her father. When Paige leaves with her father, Julie assumes that Chelsea will return to her home, but surprises Julie by asking to stay and wheedled a dinner out of the surprised professor.
It is long before discovers what is behind Chelsea wanting to stay. She tries to lure Julie into several compromising positions. Never having been in a situation like this before she is ill-equipped to deal with the lusty teen's advances.