When an Ad Exec's husband suggests a third in their bed to spice up the marriage, she invites her female trainer, who turns out to be bent on revenge.

When an Ad Exec's husband suggests a third in their bed to spice up the marriage, she invites her female trainer to join them. However, she soon learns that the trainer is insane and out for revenge for something in the past and must find a way to stop the woman before she ruins both their lives.