Trickster has a way to kill people and bring them back as zombies who want to eat other humans. If you get bit, when you die you rise up again like them. And if they eat enough other humans...they can sound like they did when they were alive, we found out later.
...Carly was among the first group infected, and she got Jim in the neck pretty quick, and they all ate Chekhov. It...was pretty bad.