The Ending Of The 5th Wave Explained
By the ending of the 2016 J Blakeson film "The 5th Wave," to say humanity's future is grim would be a gross understatement. Attacked by a mysterious group of aliens known as the Others, the Earth endures four waves of incredible devastation: an electromagnetic pulse that wipes out global communications and power and causes planes to crash, the manipulation of global fault lines, causing earthquakes and mega-tsunamis that destroy islands and coastal cities, and a modified strain of the avian flu that is transmitted via birds, killing millions. The fourth wave is most insidious, as the alien Others possess human bodies to infiltrate and attack humanity directly.
Cassie (Chloë Grace Moretz) spends the film doing everything she can to keep her little brother Sam (Zackary Arthur) safe. In the film's final scene, Cassie, Sam, and Ben (Nick Robinson) are reunited with Ben's squad in the aftermath of a rescue mission to save Sam from the clutches of Colonel Vosch (Liev Schrieber). In the aftermath of the destruction of the military base and their harrowing escape, Cassie reflects on the nature of hope.
Hope in the face of adversity
The ending of the film has Cassie reflecting on how the Others view humanity's hope as a foolish emotion, a weakness. The Others themselves use that hope against the children at the military base as Colonel Vosch and the other military personnel (themselves possessed by Others) train them ostensibly to hunt down the aliens but actually to kill their fellow humans, transforming them into the 5th wave. It's an act of cruelty to turn children into weapons and set them loose on the rest of humanity.
But Cassie remarks that humanity's ability to hold onto hope allows them to bend but never break. This hope proves to be infectious, as it allows Evan (Alex Roe), an Other sleeper agent, to defy his people and turn against the invaders, giving him the moral strength to set off the bombs and destroy the base, his first real stand against the monsters his fellows have become.
The hope for a better tomorrow
Cassie believes that humanity's ability to hope in the face of overwhelming odds will ultimately ensure their victory, and that hope makes them human. The ability to stare down the overwhelming power of the Others and believe that they can win might seem a faint hope at best, even a delusional one. But that same hope can sustain a person even when reason says there isn't any. Cassie's hope that her brother had survived, her belief that she could save him and get him to safety, sustained her in the midst of the near-impossible mission she'd set before herself.
As she sits with the young squad of soldiers at the end of the movie, she's resolved to continue the fight and free the other children the military managed to take in their evacuation of the exploding base. Her hope helped save her, and the ending hints that same hope will save the world.