Famke Janssen (X-Men, How to Get Away With Murder) and Edi Gathegi (Justified, Twilight)are attached to star in a spin-off of The Blacklist which is expected to be launched via backdoor pilot during the show’s season 3 finale on May 12. While Gathegi will continue in his current role as Cabal operative Matias Solomon, Janssen will play a new character named Susan “Scottie” Halsted. Few details are known about her role but it is thought that she may be the mother of Tom Keen (Ryan Eggold). Halsted will first appear in the May 5^th episode.

Just last month the president of NBC entertainment denied that a spin-off of The Blacklist was in the works. At the time Jennifer Salke told Variety, “The only thing I can say is we’re talking about planting some characters in the show, much in the way that we do in the world of the ‘Chicago’ shows. They could be explored as a potential spin-off, but we have in no way committed to a spin-off series.”

Watch Gathegi’s character introduction in season 3:

The “Chicago shows” include NBC’s Chicago Fire, which premiered in 2012 and has seen two successful spin-offs: Chicago P.D. in 2015 and Chicago Med in 2015. Fire and Med consistently pull in nearly 8 million viewers while P.D. is just slightly behind with an average of 6.9 million. The last of the epic Law & Order franchise, SVU, in its 17^th season and ratings for that show have fallen off from 15.2 million to averaging about 8.7 million. It’s likely heading toward its final years so NBC needs to develop another franchise it can air all year.

The Blacklist was immensely popular early on, averaging nearly 15 million viewers in season 1 and 13.7 million for season 2. That made it NBC’s highest rated fall drama – higher even than zeitgeisty shows like How to Get Away With Murder and Agents of S.H.I.E.L.D. or stable performers like Castle and Bones – until it was dethroned by Blindspot.

Then NBC moved Blacklist to its troubled Thursday night schedule, sandwiched it between Heroes: Reborn (since canceled) and The Player (brand new and little known), and ratings tanked, lowering the average to 6.8 million viewers as the end of season 3 approaches. (So much for Must See TV.) Still, the network is confident in their show and gave it an early season 4 renewal along with all three of the Chicago series.

The Blacklist spin-off is the brainchild of the original creators Jon Bokenkamp (The Call), John Eisendrath (Alias), John Davis (The Man From U.N.C.L.E.), John Fox (Dr. Ken), and Michael Watkins (Prison Break). Michael Dinner (Justified) will direct the backdoor pilot.