Reign 4×08 “Uncharted Waters” Season 4 Episode 8 Extended Promo – As Mary’s (Adelaide Kane) upcoming wedding looms, a terrible tragedy pushes Mary and Darnley (Will Kemp) apart, forcing Mary to enlist in Catherine’s (Megan Follows) help. Elizabeth (Rachel Skarsten) encounters a traitor to Spain, who petitions her to support an expedition to the New World. Craig Parker, Spencer MacPherson, Ben Geurens, Rose Williams, Dan Jeannotte, Jonathan Goad and Celina Sinden also star. Fred Gerber directed the episode written by Ben Yeon Kim and Erika Lippoldt (#408). Original airdate 4/7/2017.