The POTW is a "knight" living in a Renaissance community. From the looks of the pictures, House is enjoying playing with his sword a little too much. (Keep it clean, people!) Meanwhile, Wilson starts anew by going back to the old when he starts dating his first ex-wife again. Hopefully things will go better this time around.
Some more spoilers in the official synopsis:
House and the team take on the case of Sir William, a “knight” in a closed-off community of men and women living according to the ideals of the High Renaissance. As the team searches the medieval village for environmental factors contributing to Sir William’s rapidly deteriorating health, Thirteen and Sir William debate the acts that define honor and loyalty, especially in regard to the “queen” of the community, one of Sir William’s most frequent visitors. Meanwhile, Wilson starts over with an ex (guest star Watros) in the all-new “Knight Fall” episode of HOUSE airing Monday, April 19 (8:00-9:00 PM ET/PT) on FOX. (HOU-618) (TV-14 D, L, V)
Spoilers and photos courtesy of SpoilerTV