Like the previous two, this is a story about teamwork, courage, friendship, and identity. The teen characters may not know their past, but they know they can trust one another and work together toward securing a better, safer future. The idea that even those without power and control can unite and resist those who are oppressing them is a key theme.
There's a high body count: People die or are injured as the result of shoot-outs, assassination, and/or mass destruction, including explosions (one created by a suicide mission) and entire buildings falling. One character who's succumbing to a deadly virus asks to be killed and then has a knife fight with someone and ends up fatally wounded. A man with part of his face missing is shown several times. A couple of people who've been infested are shown transforming into zombie-like creatures. Someone plunges to their death after failing to hold on to an escape vehicle. Hundreds die during a ground/air fight.
A couple of quick kisses.
Occasional strong language includes "s--t," "son of a bitch," "goddamn," "d--k," "twat," "a--hole," "bastard," "bulls--t," "holy s--t," "what the hell," and "oh my God!"