Best friends Katie and Jess are inseparable and have always had each other's backs. When Jess begins a new serious relationship, Katie is unsure of the new perfect man and famous crime writer, Nick. She wants to support her friend's newfound happiness but is fiercely protective. Katie's obsession with Jess soon proves deadly and it is up to the recently vilified Nick to expose the bestie before it is too late.

When Nicky finds an unopened Christmas card from a high school secret admirer, she and her best friend Simone search to find and thank the anonymous author.