Simon Spier lives a normal life of a teenager, coming from a loving family, spending great time with good friends, attending an average high school. However, Simon hides something massive about himself that no one would believe is true. As it is impossible to keep a secret forever, a chat with someone anonymous makes Simon open up and confess that he too, is a gay. Unfortunately, their intimate correspondence leaks in the school website and the one thing Simon dreaded most finally happens. Now the teenager has to face his classmates, his buddies, his mom and dad. But what he wants to do most is to find who is the mysterious Blue.