As Mike and Leon decimate the military base, Ada informs Wesker that Krauser has been killed. Impressed, Wesker remarks that Leon doesn't die easily. He plans to use Leon to take care of Saddler. No matter who wins, the victor won't emerge unscathed, and he instructs Ada to finish off whoever's left. Neither Leon nor Saddler can live to see tomorrow.
Clearing out what remains of the mercenary defenses, Ada meets up with Leon just in time to witness his Plaga try to assert itself. Going on ahead to let him compose himself, she defeats the meager resistance in the cell block. But as she's about to advance, she is nearly killed by a girder.
Krauser, badly burned and injured, had survived both Leon's assault and the explosions that destroyed the ruins, and he intends to pay Ada back for her earlier humiliation. However, Ada has carefully studied his fighting style, and despite his arm, she is able to overcome her old ally, killing him for good.
Immediately after, Ada arrives in the laboratory to distract Saddler, giving Leon the precious time he needs to rescue Ashley and escape. Unfortunately, she must now fight the deranged cult leader. Through a combination of wits and firepower, she is able to defeat him and finally gets her hands on the control plaga specimen. But she does not see one of Saddler's tentacles, and is captured.
A short time later, Leon arrives on top of the structure where Saddler and Ada are waiting, he cuts her down, and begins to fight the mutated Saddler. Ada, seeing a rocket launcher on another structure, goes on an all-out offensive, racing against both a swarm of Ganados, and the timer of a great number of bombs. But she overcomes every obstacle, retrieving the launcher, and in a parallel of the same event six years earlier, tosses it to Leon at the last moment.
Holding Leon at gunpoint, she finally retrieves the plaga sample. Tossing Leon the key to a jet-ski, she takes off in her helicopter just before the island is destroyed.
- Leon can be heard during the fight against Krauser.
- After the cutscene where Ada stops Leon from killing her, she can not go back through the door she came through.