Had me the whole runtime. Ansel Elgort (along with Timothee Chalamet) is now one of my favourite and most "one to watch" actors of his generation, and delivers a good performance here. The film is affective in it's sense of danger, and I even found surprises in the plot. 4/5 for me. Perhaps a strong 3.5/5 when I consider I'm not sure I'll return to it.