Invincible #21 1st Appearance 2nd Nightwing

Return to Midnight City! Cast in the shadow of perpetual darkness, Midnight City lost its sole protector to Omni-Man, Invincible's father, as part of his plot to take over the world. Now many months have passed since the original Darkwing's death, and there's a new Darkwing in town. Invincible is curious to find out just who this guy is.