Richard the Lionheart S01 E35 A Year and a Day

After a desperate man steals Richard's horse, the squire of Fitzgeorge Castle takes him in. He can't see the man's son though they served gallantly in a crusade. The serving maid tells of a plot, where it was actually a serf that fought alongside the King, and the real scion of Fitzgeorge hid back in England.