'Shadowhunters' season 2 episode 6 spoilers, news: Magnus, Alec go on their first date; 'Game of Thrones' alum joins cast as Sebastian

Isabelle's (Emeraude Toubia) secret might be revealed on the upcoming episode of Freeform's supernatural drama "Shadowhunters" season 2.

Titled "Iron Sisters," next week's episode will see Clary (Katherine McNamara) and Isabelle determined to get information about Valentine's (Alan Van Sprang) plans. As a result, the duo embarks on a mission to consult the Iron Sisters at The Citadel. Upon reaching the area, bigger truths than what they initially expected are revealed.

Meanwhile, Simon (Alberto Rosende) and Maia (Alisha Wainwright) embark on a mission of their own. Following the demon attack at the Institute, the two characters must find Luke (Isaiah Mustafa). Elsewhere, Magnus (Harry Shum Jr.) and Alec (Matthew Daddario) celebrate a new milestone in their relationship as they finally go on their first date.

On other related news, "Game of Thrones" alum Will Tudor recently joined the cast as a recurring guest star. Tudor has been tapped to play Sebastian, a charming and highly educated Shadowhunter with exceptional fighting skills. He winds up at the New York Institute after becoming friends with one of the show's key characters. Tudor's Sebastian will make his first appearance in the second half of season 2 which airs later this year.

In Cassandra Clare's "The Mortal Instruments" book series, Sebastian Verlac was a Shadowhunter and a cousin of Aline Penhallow. After his parents' deaths, he was raised by his aunt Élodie Verlac, who later took over as the Paris Institute's head. Sometime in 2007, he was killed by Jonathan Morgenstern in an effort to take over his identity. It remains to be seen how the show will come up with its own version of the said character.

Aside from his stint on HBO's epic drama, Tudor's acting credits include "Humans," "Tomorrow," "Bonobo," "Mr. Selfridge," "The Red Tent," and "In the Club."

The second season of "Shadowhunters" airs every Monday night at 8 p.m. ET on Freeform.