Deadly Is the Black Widow's Bite!

S1 E12: A new heroine named the Black Widow joins the team and shows the boys she can kick butt even better than them. But we soon learn she is really the shape-shifting Mystique, sent by Doom to infiltrate and get at the fractals. She nearly succeeds and leads the Squad into a Lethal Legion ambush. But Nick Fury may just have provided their ace in the hole. . . Screaming Mimi turns on the villains, revealing herself to be an undercover SHIELD agent named Songbird!