Holden and Fred deal with infiltrators on Tycho. Drummer's past comes back to haunt her. Amos returns to Baltimore. Alex and Bobbie's investigation on Mars leads to rogue soldiers.
Quest roles:
Keon Alexander(Marco Inaros), Chad L. Coleman(Fred Johnson), Anna Hopkins(Monica Stuart), Jose Zuniga(Bull), George Tchortov(Leveau), Michael Irby(UN Admiral Delgado), Bahia Watson(Sakai), Frankie Faison(Charles), Tim DeKay(Admiral Sauveterre), Stacey Roca(Lydia), Nazneen Contractor(Ashanti), Amanda Martinez(Colony Ship Captain), Basel Daoud(Belter Pirate Captain), Sandrine Holt(Oksana), Lara Jean Chorostecki(Lt. Babbage), Samer Salem(Josep), Stephen Tracey(Bertold), Amanda Cordner(Hutch), Jasai Chase-Owens(Filip Inaros), Dayton Sinkia(Theo), Idrissa Sanogo(Dock Tough), Lily Gao(Nancy Gao), Ryan Hollyman(UN Chief of Staff), Wilex Ly(Serge), Vanessa Smythe(Michio), Cole Pollock(Angry Boy / Timothy), Gabriel Iglesias(Street Kid), Jacob Mundell(Erich), Andrew Fleming(Gavin)