The Infinite Sea

Plot

A few days after the events of the first novel, Cassie, Ben and the rest of squad 53 have taken refuge at a hotel, which they call "Walker Hotel" in honor of Evan Walker, who is thought to be dead after destroying Camp Haven. Ringer, believing that their refuge in the hotel will not last, goes out searching for a cave system mentioned on a brochure. Teacup, who she had grown close to, sneaks up to Ringer who shoots her, mistaking Teacup for a Silencer. A helicopter flies in and they are both captured by The Others.

Cassie and the others anxiously await Ringer. They realize that Teacup has gone missing, and Dumbo and Poundcake set out to find her. They return empty-handed.

Later, it is revealed that Evan Walker had survived Camp Haven's destruction, and is wounded and hurt. He gets rescued by Grace, a fellow Silencer like him. They head to her makeshift home. They spot Cassie at the hotel from an interstate on their way there. After one of Grace's hunts she tries to seduce Evan, but he attacks her. While escaping her house, Grace shoots at him, though Evan thought he killed her. She lets him go, knowing that he will lead her to Cassie. While he rests and Grace confronts him, they are attacked and Grace is shot at, giving Evan the opportunity to escape.

He finds the hotel they stay at, and disarms Ben in a misunderstanding, though Ben stabs his leg. Evan finds Sammy and, seeing the gun in his hands, dives at him. Cassie shoots him once and he is rendered unconscious. Ben angrily awaits his awakening. Cassie defends him while Ben throws constant insults toward him. In the midst of this, they hear a helicopter approach. However, it quickly flies off. Then, they see a small girl walk down the hallway, who Sammy identifies as "Megan". She says that her throat hurts before passing out.

The group cares for her, though when Evan awakes, he warns them not to, explaining that The Others planted a bomb in her throat rigged to detonate on high concentrations of carbon dioxide. The group moves outside a distance from the hotel, while Cassie and Evan stay behind to remove the bomb from her throat. With a struggle, Cassie manages to safely remove the bomb and she contains it in a plastic baggie. Ben and Poundcake have been collecting CO2 canisters so that the bomb can be detonated at a safe distance away.

Grace appears as Cassie and Evan finish the operation. She forcefully kisses Evan in front of her. As the squad appears, chaos begins, Poundcake is shot. A chopper flies in and in the struggle, Grace disappears to destroy the helicopter and kill the pilot. Evan tells Cassie of a pod sent down from the mother ship to extract Grace and will be at her temporary home. He shows her how to find it and shows her the bomb they removed from Megan's throat. Sammy takes the bomb as he rushes by on his way out. Evan makes Cassie promise "to end it" and insists that he be left behind. As she knows she has no other choice, Cassie kisses him and leaves.

A short distance from the hotel Sammy turns and starts running back, Cassie catches him and he says that he dropped the baggie, the hotel explodes, Cassie thinks Evan sacrificed himself. Unable to carry him, the group had left a mortally wounded Poundcake and continued to move away from the hotel. Poundcake crawled back to the hotel found the lost explosive device and blew it up an arms length from Grace.

Ringer has been taken to another "training" camp, much like Camp Haven. Colonel Vosch has taken over command of the camp. Ringer semi-befriends a recruit named Razor, who knows of the conspiracy and that the officials at camp are actually The Others. Vosch taunts Ringer with games of chess and statements about what her father would think about her, how proud he would be. Ringer questions about the whereabouts of Teacup. Vosch tells her that she, whose name is revealed to be Allison, is alive. Vosch also continuously preaches to Ringer that "rage is not the answer." She holds an on-and-off friendship with Razor, as well. She also finds out that he loves to talk about everything, including him revealing his true name, Alex, and that he earned his nickname after he cut himself with a razor in the shower.

One day, Vosch, Razor, and a woman named Claire, who despises humans, enhance her with the 12th system (neural chip and nanobots), a piece of Other technology designed to strengthen the human anatomy.

Ringer and Razor build a plan to escape. The plan is carried out successfully, Ringer kills Claire and disables Jumbo, knocks out Teacup, and forces a pilot to fly them in a helicopter, before it crashes the pilot, Razor and Teacup bailout. Ringer jumps without a parachute and lands in an ice covered lake. After meeting at the crash site, Ringer soon discovers that Razor was secretly working with Vosch, she had sensed something through the 12th system when she kissed him prior to the jump from the helicopter. She knocks him out and heads to the warehouse, which had been converted to a hospital the time of the 3rd Wave. She finds Vosch in it, and he openly invites her to a fight. Vosch wins easily and It is after this that we learn that Silencers were never actually "Others", just humans enhanced by the 12th system neural chip that contains a construct program to make them believe they are "Others", never controlled or linked to the "Others", but it is unclear if Vosch is human. Razor is charged with guarding and helping to heal her. Ringer and Razor reconcile and he slept with her afterwards.

When they return to base, Vosch questions Ringer about what the "solution" is, she states that the "Others" don't mean to exterminate all humans, Vosch states that the "Others" could have have simply eliminated all humans by dropping a big rock on them and hints there is a specific goal to be gained through the wave attacks. Ringer tells Vosch he has enhanced her to hunt down and kill Walker, that he needs someone like her because the destroyed drones were meant to track the enhanced humans, not normal humans. Razor whispers to Ringer about the leverage Vosch has on her because of Teacup and proceeds to shoot and kill Teacup. Razor in turn is shot and dies. The chaos gives Ringer a chance to escape by diving out a window.

At the end, Cassie and squad 53 are recovering from the explosion. From the woods, Evan emerges and Cassie goes to meet him.