Mary and Francis are forced to rely on one another when the castle is taken hostage, and Catherine shocks everyone when she makes a surprising proposal to try to save their lives. Meanwhile, Bash's mother Diane tells Bash of her plan to have him legitimized.

When Mary and Bash are captured and forced to return to the castle, they discover Catherine waiting and even more determined to keep Mary and Francis apart. Francis learns of the prophecy, but his determination to wed Mary changes everything: in love in politics, tearing the bond of brothers apart, and hardening Catherine's resolve to destroy Mary at any cost. Caitlin Stasey,