The Last Star" is the third and final book of "The 5th Wave" trilogy. The book continues the story where the previous book ended. So I recommend that you read both previous books before you read this one. I must also say that this is a young adult novel, meaning that it has profanity and the occasional curse word. So if you're not mature enough or don't like these types of books then don't read this one.
Now that, that is out of the way, to the plot. The story follows survivors of an alien attack that plans to kill all of the humanity as they plot to kill the visitors, referred to as the "Others". Cassie, short for Cassiopeia, is the main character of the story and the bossiest and emotional. Evan, Cassie's crush, is a silencer, a human-other hybrid that the Others sent to clean up survivors but defects to the human side for Cassie. Sam, short for Sammy, and also Cassie's younger brother. In the story, he changes a lot, from a child that goes from being terrified of anything to a battle-hardened soldier that does not fear anything. Ben, a.k.a. Zombie is the jock of the group, he has a big ego and is very athletic. Another character found in the story is Marika, a.k.a Ringer, she ends up helping a silencer's plan to kill Evan to help out her fellow survivors. Those are the main characters of "The Last Star", but sadly one of them dies.
In my opinion, it was very cliche to have the main, main character, Cassie die. She died by blowing up the Other's mothership, saving humankind but also killing her self. Cassie was the most emotionally developed character and I didn't like it that she was just thrown to the side. I think that having a fairly new character take Cassie's place in destroying the mothership would have been better.
Considering this is the finale to the series it was a bad choice to kill off Cassie. This leaves the other characters underdeveloped because Cassie was their foundation, requiring another book that will never come. It is okay to leave the reader with unanswered questions because it makes them want more but there is no more, this was the last book. "The Last Star" simply just left us with too many unanswered questions. The book is overall good but the ending, in my opinion, is bland. I would recommend readers to be creative and make up an ending for the book if they aren't pleased with the books ending.