Between 7:00 AM and 8:00 AM, enter the Safe House’s security room and give Katey her Zombrex shot to prevent the world’s cutest zombie from emerging.
In all seriousness, if you don’t give Katey the shot during this brief window of time, you won’t be able to enjoy the game’s true ending.
Giving Katey Zombrex completes your first Case File task. You’re now able to view the entire Case File from the pause menu, helping you keep tabs on upcoming events.(Stacey will regularly remind you about active cases as well.)
You’re given the option to save your game after you clear a case; go ahead and do so now that you’ve given Katey her Zombrex for the day.