Reign 4×13 “Coup de Grace” Season 4 Episode 13 Extended Promo – Darnley (Will Kemp) teams up with John Knox (Jonathan Goad) to strip Mary (Adelaide Kane) of her throne, which will leave a close friend of Mary’s dead. Elizabeth (Rachel Skarsten) must banish Gideon (Ben Geurens) from court at the request of her future husband (guest star Steve Byers), while Charles (Spencer MacPherson) takes a bold stance against his brother Henri (guest star Nick Slater). Dan Jeannotte, Celina Sinden, Megan Follows, Craig Parker and Rose Williams star. Megan Follows directed the episode written by John J. Sakmar and Kerry Lenhart (#413). Original airdate 5/19/2017.