The May 5 episode of Reign is called “Dead of Night” and The CW has now released an official description to promote it. Here’s that write-up:
MARY LAUNCHES A COUP AGAINST ELIZABETH — Mary (Adelaide Kane) and Darnley (Will Kemp) are at odds as they put their plan to seize England into action. Elizabeth (Rachel Skarsten) is conflicted about her feelings for Gideon (Ben Geurens) as she attempts to find a Catholic to marry. Catherine’s (Megan Follows) son Henri (guest star Nick Slater) attempts to claim the throne from Charles (Spencer MacPherson) with the support of Spain and Narcisse (Craig Parker). Dan Jeannotte, Jonathan Goad, Celina Sinden and Rose Williams also star. Deborah Chow directed the episode written by Wendy Riss Gatsiounis and Drew Lindo (#411). Original airdate 5/5/2017.
UPDATE: We now have photos! Enjoy.