I will not get into the aspects of movie making or storytelling. That part was well done. It was not hard to understand the concept of the time reset or the construct of the creatures. I want to first run past the film and then compare it to the story in the book. Here’s Edge of Tomorrow : Movie vs Book (All You Need Is Kill).
Edge of Tomorrow : Plot Synopsis
The basic concept is that the Omega is the main alien unit with multiple Alphas. The death of an Alpha causes the Omega to revert time back and anticipate the course of events. This way the alien life form never loses a battle. Poor humans don’t know this and they run into their imminent deaths.
The blood of the Alpha on Cage, gives him the power of reset too. So now every time he dies he resets back to the start of the previous day. Rita notices that Cage sees the future; she too had that power once so she asks Cage to go meet her when his day resets. The rest of the movie, the two of them plot on various strategies to get to the location of the omega which comes to Cage as a dream vision.
Little do they know that the Omega simply has identified a human (Cage) with the ability to reset and buy giving the vision of a fake location to itself, the Omega can plan a trap for Cage to drain his blood which will remove his powers to reset time. This has already happened to Rita in the past and that is how she loses her power to reset. Cage escapes the trap by drowning himself and resets to the previous day.
Rita and Cage now choose an alternate strategy to find the real location of the Omega using a device. There is not much explanation to this device but helps locate the Omega based on the Alpha’s blood in Cage.
Cutting it short to the end, Cage and Rita with the help of the squadron land up in Paris and plan an attack on the Omega. With their last breath, they succeed to kill the Omega. Cage is dying by bleeding out. But the Omega’s blood enters him and he now resets the time back by a day. This event of absorbing the alien blood happens at a time earlier than the previous time. Therefore the reset of time happens to an earlier point (on the chopper) instead of his usual reset point on the airfield.
Edge of Tomorrow : Plot Hole
The death of the Omega is an event that is created by Cage. Since the Omega itself died, it could not reset time to prevent its own death. Cage can now be assumed to be the Omega (with no Alphas). So he can continue to have memories of the event of the Omega’s death – yet to occur. As far as the rest of the world goes, they should have only been shocked that the aliens are all dead, but shouldn’t know about an explosion in Paris. The explosion in Paris is yet to happen as far as the rest of the world is concerned. The news however reports of an explosion. This part makes little sense.
A suitable ending would have been – the aliens are dead, but no one knows how and remains a mystery to the world (because the event has not yet happened, but the consequence is felt). Only Cage knows what happened thanks to the Omega’s blood in him.
All You Need Is Kill : Plot Summary
This is the original story based on which the movie Edge Of Tomorrow was produced. The lead in the book is Keiji and the movie had Cage. Rita is the same name as she belongs to the American unit. Rita Vrataski is a veteran Special Forces soldier called the Full Metal Bitch by other soldiers.
What are the Mimics
There is a quick background about the aliens here. The Mimics, as they are called, are actually not the aliens. They are the creatures sent to terraform Earth to make it suitable for the aliens to inhabit. They eat the Earth and excrete a material toxic to humans, but suitable to the aliens.
Mimics are shown to be constantly adapting to the need. While the first version of them are sluggish and easy to kill, the later adaptations are swift and very hard to win a battle against. The Mimics are in networks. Each network has a Nexus and many Antennae. Both the Nexus and the Antennae can trigger a reset of time. Nexus and Antennae don’t look different to the regular human eye.
In the rare case of killing an Antenna Keiji is caught in one such time loop. Every time he dies, he wakes up a day before the battle. He keeps track of the loop number by quickly writing it on his wrist. Rita has been stuck in her own loop as well in the past. She realizes that Keiji is stuck in a loop and she asks him to meet her past self so that they can plan ahead to figure their course of action.
And so they meet for the first time over 160 times. They try out a series of strategies. The main one involving a battle axe because guns run out of bullets and axes, well, don’t. They figure that to stop the time reset, all the Antennae have to be killed before the Nexus is killed. So they meticulously start killing all the Antennae and then kill the Nexus. In spite of this, the loop is reset. In their last attempt, they take out all the Antennae and Rita begins to attack Keiji because, according to her theory, they have been looping for so long that they have become Antennae like. She is an Antenna to his loop and he is to hers. So to stop the looping one of them needs to die and the survivor has to take out the Nexus. Keiji and Rita have a gruesome battle and Keiji actually ends up killing Rita. He then proceeds to kill the Nexus. The time doesn’t reset. Rita stays dead, and he’s commended to be the war hero. Keiji continues his battle against the Mimics.
The ending in the movie is nowhere this badass, the film has a much more happy ending.