I don't think I have rated a book 4 ⭐️ when I disliked all the main characters before.
The pace and the story captivated me from the start, I read this one quickly in 2 sittings. 
I was suspicious of Carl from the start but I couldn't put my finger on why. Patrick came across as a douche bag and main character Allison was unlikely. Yet somehow I still very much enjoyed this story.