Kristen, David and Ben are called to investigate an insidiously addictive Christmas song that's spreading among an increasing number of students, and the dangerous relationship between online influencers and their impressionable young followers.

As Leland assists convicted serial killer Orson Leroux with having his conviction overturned, Kristen is called into court to testify while her daughter, Laura, undergoes emergency heart surgery. Also, while paying a visit to a woman in need of spiritual advice, David fears for his safety after witnessing her evil instincts firsthand.