After recovering from a family tragedy, Phil Lester does his best to try to continue with his life like before. It's difficult, but he manages. His mother is still a bit of a mess and he doesn't talk to his brother as much as he'd like to, but he manages. Phil's friends are aware of all that's happened and they try to comfort him, but they don't understand everything in the way that Phil wishes they could.
One day, however, a new student arrives at Phil's high school on a motorcycle and wearing nothing but the color black. He's dashing, quiet, and overall, mysterious. He becomes the talk of the school, everyone wanting to know about this mysterious newcomer and where he came from.
Phil's curiosity gets the best of him, so when he spots the new kid in his chemistry class, he can't help but introduce himself to who he would soon know as Dan. Dan actually ends up being an extremely cool and nice person, and Phil is excited to get along with him and form a friendship.
However, there's something off about Dan.
Dan, also known as Agent Ten, just lost his greatest mentor, and has been sent on what he's been told will be an extremely difficult mission to perform an assassination. His job is to meet, study, and assassinate Phillip Lester.
When Dan finds his target introducing himself to Dan, Dan begins to think that this will be his easiest assassin to date...That is, until all of his assassination attempts fail.
And, after getting to know his target a little better, Dan finds himself falling hopelessly in love with Phil Lester, and therefore unable to perform the assassination as instructed.
However, there's something off about Phil Lester.
And when they find out each other's secrets...
All Hell breaks loose as Phil tries to get a grip on his sanity, and Dan, his humanity.
"Phil Lester is the literal sunshine of my life. If I didn't have him in my life, I may have been dead by now. Every day still sucks, but whenever I'm with Phil, my heart remembers that life is worth living. The only reason my life is worth living is to be next to Phil. To see him smile, to hear him laugh, to listen to his voice, to watch him move...everything. Everything that he does brings the much-needed light into my life."
Dan Howell has many struggles within himself, despite his successful YouTube career. The only one who truly helps him is his best mate, Phil Lester. Dan has been madly in love with Phil since the first day they met. However, Dan knows that it is inevitable that Phil will never return the feeling because he is only interested in women. As Dan attempts to battle his own demons, Phil seems to be quite happy and even ends up dating a beautiful girl. Unfortunately, this makes Dan's mental state even worse. What will happen to Dan? Will he ever confess his strong feelings for his best friend? Will he ever overcome the ongoing war in his head?