Episode seven is to air March 3rd on the CW at 9/8 central.
The 100 03×07 title: Thirteen
Official synopsis:
FLASHBACK TO A DARKER TIME — Lexa (guest star Alycia Debnam-Carey, “Fear the Walking Dead”) tries to maintain peace and order within the clans, and Clarke (Eliza Taylor) uncovers a strange and game-changing truth. Meanwhile, a flashback takes us into the darker chapter of humanity’s past. Paige Turco, Isaiah Washington, Henry Ian Cusick, Bob Morley, Marie Avgeropoulos, Devon Bostick, Lindsey Morgan, Christopher Larkin, Richard Harmon and Ricky Whittle also star. Dean White directed the episode written by Javier Grillo-Marxauch (#307). Original airdate 3/3/2016.