Castle‘s season finale just got a lot more interesting.

Sources confirm to TVLine exclusively that Battlestar Galactica and Dollhouse vet Tahmoh Penikett has landed a potentially recurring gig on the ABC drama that kicks off in the emotional May 7 finale.

His role, not surprisingly, is shrouded in secrecy.

What we can tell you is that his character’s name is Cole Maddox and he’s cold, calculated and has a military background.

In other words, he’s bad news.

Penikett’s recent TV credits include guest stints on Haven, Fairly Legal and The Killing.