Kate and her husband, Ron, attend a dinner party where they meet another couple, Peter and Jill. Kate and Peter only exchange a few pleasant words, but Kate is suddenly overcome with a burning desire for Peter. Her fixation on him results in an intense, passionate encounter between the two. Confident that her life can now go back to normal, Kate never considers that Peter may not be so willing to move on. Not long after their affair, a masked man barges into the café Kate is sitting in with her best friend, firing an assault weapon indiscriminately into the crowd. This tragedy is the first in a series of horrifying events that will show Kate just how grave the consequences of one mistake can be.