Story: Avengers, vol 1 #78
Background: Captain America is ambushed by M'baku, who has a goal to take down all of the Avengers. He succeeds in defeating Captain America but flees when the rest of the Avengers appear. He then kidnaps Monica Lynn to force T'challa in facing him alone.
[Scan Tip: Click to enlarge the images and they are easier to read. You can scroll through them all that was as well. --- Shadow]
The ol' trick mannequin bomb. Who knew M'baku was so clever?
T'challa ends up thrown in a dungeon of sorts and listens to M'baku's master plan and sees the formation of the Lethal Legion.
The Avengers and the Lethal Legion eventually fight. Spoilers... Avengers win.