- "You're the ones who caused this nightmare! You ruined Santa Cabeza and started all this!"
- —Isabela Keyes
Isabela Keyes is the younger sister of Carlito Keyes, and appears in both Dead Rising and Dead Rising 2: Case West. She originally wanted to help her brother take vengeance on the American people for what they did to her hometown of Santa Cabeza. Over the course of the story, she has a change of heart and decides to help Frank West in stopping Carlito's plan after seeing what her brother has truly caused.
At first, Isabela Keyes helps her brother take vengeance on the American people, but has a change of heart after she realizes that Carlito has gone too far. She becomes an ally to Frank West, and helps him discover the truth behind the Willamette Incident.
After Ed's helicopter crashes, Isabela comes to the helipad and saves Frank from the zombies, but later informs him that he is now infected. Frank then collects supplies required for the zombification cure. Once Frank has acquired the necessary items, Isabela creates a temporary serum to delay the effects of zombification. She then sends Frank to capture 10 queens, which are used by Isabela to fashion a zombie repellent pheromone. While Frank is looking for the items and queens, however, he discovers that there is a gaping hole in the clock tower, as a result of Ed DeLuca's crash, to which he tells Isabela. She and Frank then decide to descend into the dark depths of the unknown, as a way for them both to escape the mall.
After long walking through the tunnels, the duo reach a rusted gate, where the military has established a defensive perimeter. Frank activates a lever, raising the gate and distracting the military long enough for them to enter, where they promptly face the commander of the military clean-up operation, Brock Mason. Frank commandeers a humvee while Isabela manipulates the machine gun mounted on the back. After the fight Isabela and Frank's Humvee is tipped over, Frank engages Brock in combat, while Isabela climbs onto the top of the car to avoid the zombies. After Brock is killed, the game ends, with Isabela being stranded ontop of the car, surrounded by zombies. As the camera pans out for one last time, she and the jeep are mysteriously absent; in the credits it states that Frank was able to survive and spread the story of what really happened at Willamette and Santa Cabeza. She is one of the very few, besides Frank, Otis, and any survivors Frank rescued, that officially survive Dead Rising.
While she doesn't make a physical appearance in the series. Isabela is featured in a flashback recalled by Frank West during his first meeting with Rebecca Chang. Frank mentions that after escaping Willamette, he and Isabela were separated by homeland security agents who intercepted them after their escape helicopter landed.
Agent Cornell of the DHS orders his men to take Isabela into custody for her and her brother's involvement in the Willamette Incident. When Frank tries to intervene, Cornell explains that the DHS had been aware of what Isabela and Carlito had been up to for some time, and expresses his thanks for killing Carlito. Cornell also warned Frank that should he intervene, the DHS could just as easily make up a story about him being Isabela's co-conspirator, and arrest him for it.
All that Frank West can do is watch helplessly as Isabela Keyes is taken away.
It is revealed by Stacey Forsythe that Isabela was working on a cure for zombification for those who have been bitten, but not yet turned.
Isabela is shown to be working for the Phenotrans Corporation as a way to atone for her and her brother's crimes in Willamette. Working from a secure lab in a Phenotrans Facility, she attempts to create a cure for the zombie plague, but Phenotrans doesn't mass produce it because they know that it would hurt their profits. Towards the end of the game, Isabela is knocked unconscious by Harjit Singh (Chief of Security for the Phenotrans Facility), and is taken hostage by Marian Mallon (Phenotrans Facility Director) as the facility self-destructs. Her whereabouts are currently unknown.
Isabela appears in Al Fresca Plaza at 1:00:00 - 1:07:00 and the North Plaza at 6:19:00 - 7:00:00 and is armed with a handgun and motorcycle. When killed, she drops a pack of cookies, a carton of milk, an energizer juice drink, a pick ax, and a shotgun.
Isabela attacks Frank while on her motorcycle, armed with a handgun. If Frank remains out of the open for too long, she will drive away to a hallway in North Plaza, and will only return once Frank steps into the open.
Motorcycle: Isabela will attempt to run over Frank if he is in the open. This attack causes two blocks of damage and will throw Frank into the air.
Handgun: If Frank is in a location that cannot be reached by the motorcycle, Isabela will stop and pull out her handgun. She will fire at Frank, each time causing half a block of damage.
- If Frank leaves the area or enters Seon's Food & Stuff during the battle, Isabela will flee and Frank will miss out on all remaining cases. This also happens if Frank doesn't defeat her before midnight.
- When she is being escorted in Overtime Mode, she cannot be equipped and has to hold hands or be carried, but she is also immune to all damage.
- In Infinity Mode, she will appear at Al Fresca Plaza, on her motorcycle, carrying cookies, milk and energizer from 1:00:00 to 1:19:00. She appears again at North Plaza from 6:19:00 to 7:00:00.
- During the boss fight, Isabela will sometimes become invulnerable to all attacks due to a glitch.
- Despite being pictured with a Barrett M82 in her concept art, she does not use the Barrett M82 anywhere in the game. She does use the Barrett M82 in an old trailer while clearing out zombies in the Entrance Plaza.
- In Dead Rising 2, her name is spelled "Isabella", this can be seen with the subtitles on.
- Isabela is the original creator of Zombrex, which she first makes for Frank using many materials.
- Isabela reappears in Dead Rising 2: Case West and is Frank's Source
- Isabela's nationality is debatable, since the Pachamama term and festivity is celebrated in Argentina and Bolivia.
- In Dead Rising 2: Case West when you enter the Director's Office you can see Isabela standing in the secure lab.
- Isabela is voiced by the same person (Kim Mai Guest) who voices Xian Mei, a character in another popular zombie killing videogame, Dead Island.