S1E9 · Critical Mass

Complete story — includes the ending

A flashback from seven weeks prior shows the lead-up to Julie Mao's gruesome death; the Scopuli, with Julie as part of the crew, are on an intercept course with the Anubis, which they believe to be transporting a weapon from Phoebe Research Station to Eros on behalf of Julie's father, Jules-Pierre Mao. The Anubis ambushes the Scopuli, killing the crew and imprisoning Julie while revealing their intent to destroy the Canterbury and antagonize Earth and Mars into a war. After discovering the organic reactor substance - the protomolecule - has killed everyone aboard, Julie vents the Anubis, leaves it on an asteroid with an OPA beacon, and takes the ship's shuttle to Eros. An increasingly infected Julie tries in vain to contact Anderson Dawes for rescue on Eros before dying alone in her hotel room. In the present, Fred Johnson broadcasts evidence that the stealth ships were built on Earth. After Miller and the Rocinante crew flee the hotel, Julie's body is tracked down by Dresden, a scientist working for Mao. Dresden harvests her infected blood and informs Mao of his daughter's death, to which Mao responds, "proceed as planned". Under the guise of a ship explosion and radiation leak, Eros mercenaries working for Dresden and Mao place Eros into lockdown and seal the poverty-stricken citizens into radiation shelters after infecting them with Julie's blood. Most of the Rocinante crew head back to the ship, while Miller and Holden go to investigate the shelters. Discovering their true purpose as incubators for the infection, with everyone inside dead or dying, they also receive a lethal dose of radiation. Avasarala visits Frank DeGraaf's widowed husband, Craig, and steals data drives related to an Advanced Fusion Prototype which looks like the reactor on board the Anubis.