Hazel and Augustus, two teenagers who meet in a cancer support group travel to Amsterdam and discover the depths of love, pain, and sacrifice.

Agree with dgp

A teenage girl afflicted with stage 4 cancer risks her fragile health to fulfill her dream by traveling to Amsterdam to meet the author of her favorite book. (28 words, 157 characters)

The logline does nothing to evoke the chemistry of the love story between Hazel Grace Lancaster and Augustus Waters, but the focus of a logline is the plot. And Hazel Grace's dream of meeting the author of "An Imperial Affliction", who resides overseas in Amsterdam, is the motivation for the plot that frames the story and the relationship of the two teens, both cancer survivors.

The movie was not based on a story concept that came out of nowhere. It was an adaptation of a best-selling YA book. The concept had been pre-tested and proven to be a winner. So its fate was not contingent on a logline.

A lot of the core elements of a logline are missing.

-Protagonist: who is the Protagonist. Hazel or Augustus? You must make that clear.
-A clear goal: "discover the depths of love..." is very vague and is very unclear about what exactly the protagonist's goal is
-Inciting incident: Is it when they travel to Amsterdam?
-Antagonist: and how and what stands in the way of the Protagonist's goal