Ten years after the breach between worlds at the bottom of the Pacific Ocean was closed and the invasion by titanic monsters stopped, the world finds itself once again threatened by the creatures, known as Kaiju. When Jake (Boyega), the son of a hero from the war against the Kaiju, finds himself in trouble with the law, he's given a choice by his adoptive sister Mako Mori (Kikuchi): either join the Pan-Pacific Defense Corps or face time in prison. Not long after he makes his choice, however, new breaches in reality open up around the world and new monsters emerge, leaving Jake as one of humanity's last defenders, and one of the few able to face the new threat to all life on Earth.
Born with a rare genetic disorder, teenager Katie (Thorne) has a life-threatening sensitivity to sunlight and is completely housebound during the day. While out after dark one night, she's asked out by her handsome crush Charlie (Schwarzenegger), who is unaware of her condition. As the two begin a romance, they find themselves drawing ever closer, but Katie finds herself unable to tell Charlie the truth, despite her well-meaning father (Riggle) warning her that keeping him in the dark is the wrong thing to do.
Sawyer (Foy) has been terrorized by a stalker (Leonard) for two years, and visits a hospital hoping to join a support group for harassment victims. After her initial consultation, though, she signs documents without realizing that she's committing herself to spend time in the psychiatric ward, and when she discovers that one of the orderlies is her stalker, she begins to question her own sanity even as she tries to convince the staff that she doesn't belong there.