You also play the game as Moira's dad Barry, who is paired with a creepy little girl named Natalia. The four of you shove crates, turn cranks, and slaughter gooey monsters in order to prevent something only a madman would try to explain in 21 words: Alex Wesker, a genetically engineered woman, wants to transfer her mind into Natalia to take over the world with tentacled abominations. And like every Resident Evil game that was and will ever be, this goes terribly wrong, she explodes into monster form, and you slowly fill her with bullets until she dies.
From there, the game can end multiple ways. Most commonly, Claire rescues everyone in a chopper and the world is saved. In another, Moira is crushed to death, Claire ends up in a coma, and Alex takes over the little girl's body. There's more bad news. Barry, who has spent most of his adult life blasting holes in global threats, can't bring himself to execute a child ... even one that contains the mind of a Nazi zombie lord. So he lets her wander off to destroy the planet.
So how do you prevent this horrible outcome? Well, in order to get the good ending, you needed to have shot the previous boss, Neil, with Moira, who as we mentioned refuses to use guns. If you're wondering, her dislike of firearms started when she was a child and she accidentally shot her sister Polly, a tragedy that could have been prevented if only Polly had her own gun.