“The parasite has either evolved, or something unforeseen has caused it to go apeshit. It controls its human hosts with the intention of spreading as much as possible.”
With their numbers dwindling faster, it's not shocking almost everybody has now intertwined with each other as their tales of survival make towards the end. Krista has practically gone mad at the prospect of saving her son Nelson, gone is humanity and consciousness, instead replaced with icy cold calculations. Angela and James made the mistake of ringing her doorbell, then eating the drugged food she presented them. As they fel unconscious, they would wake up tied up in the first bedroom as she announced her plans to feed them alive to her son. Interrupted by a knock on her door, she welcomes Ben inside who is quick to knock her out with a brick. Cheering at his own survival and chance to avenge Angela from the clock tower, he didn't pay attention to Nelson until he lost two fingers to him. Stabbed through the chest with a fire poked from Krista, she would die cradling her dead son in her arms as James and Angela made their escape.
“Toxoplasma gondii,” Daniel repeated. “A parasite that can only thrive in the intestines of felines. It infects rats and affects their brain somehow, mind-controlling them to allow themselves to be eaten by the cat. The parasite itself does not harm humans. There have been speculations that it can affect behavioral changes to a small degree, but there’s no evidence to support such claims. Most people live with it without even knowing they have it.”
Waking up in white clothing and locked inside a cell Pierce and Shepherd remain separated for weeks as they undergo experimental testing. Injected once a week with a serum alleging to slow down the parasites’s progression, they unknowingly were speeding up the advancement. Suffering horrible abdominal cramping, they both knew their time was coming to an end. Determined to keep this plague out of the rest of the world, Shepherd managed to break away and allow the infected inside the underground base. Armed with an explosive, they made it to the basement where they would detonate it in the generator. Feeling the effects, Shepherd sacrificed herself to the mission while Pierce fought one final battle with Reynolds. Meanwhile, Daniel is grieving the death of Melissa, as she quickly succumbed to the fever and infection. Tossing her body into the break room, he holds in his hands the key to the escape tunnel but has no intentions of using it. When James and Angela make it to Welco Labs, he recognizes her as the cleaner he got a job for and welcomes them inside. Using his own life as the sacrifice, he passes off the key and goes head to head with the infected to buy them some time. Reaching the hidden entry, Angela leaves herself on the outside as her eyes were already becoming bloodshot with the infection. Giving him the photographs of herself and her daughter, she makes him promise to go to her and give her the answers she can't anymore. Turning away, she's killed by infected as he makes the last legs of this journey alone. Coming out miles outside the city, he sets off to Salem in search of Riley.
“I’m sorry. I’m so sorry. For everything.”