Marion to the Rescue - S1.E6

Marion sets out to save her young cousin, Iris, from a marriage arranged by her evil sister-in-law, Lady Isabelle, to Lord Garth. Isabelle has told Iris that her intended, Thomas of Glockshire, was killed in the crusades, but he is actually on his way back. He meets Robin and his men, who are on their way to help Marion. Marion saves Iris, and returns to Sherwood, only to find that Robin and his men are now catives in Isabelle's castle, and Marion must now return there to rescue them.