The Death serum is a substance used by David and Jeanine Matthews. After being injected with it, or in the case of Allegiant, sprayed with it, you will die fairly quickly. When Tris Prior surrendered herself for testing, Jeanine attempted to use it after Tris fulfilled her requirements, but it was actually the different, non-lethal paralyzation serum dyed purple. The real serum was in Peter Hayes's hands, who felt he owed Tris. It is also noted that strong Divergent characters can resist the death serum when Tris resists it in Allegiant.
- The Death Serum is considered the serum of Erudite.
- In Allegiant Tris describes that the serum smells like smoke and spice, she also says that you feel the blood replaced with molasses, and the bones with lead, you also feel your body falling to the side.
- Tris resisted it thinking about the people she loved and the ones who died for her, and the flame of life.