An urgent note supposedly from Black Panther has brought Captain America to the roof of Avengers Mansion, where he is attacked by Panther's foe Man-Ape, who actually sent the message. After a fight Man-Ape throws Cap off the roof, just as the current Avengers less Panther come out to see what's happening.
Quicksilver dives off the side of the roof, grabs Cap's hand, and vibrates his legs to slow their fall. It's not enough, but Vision has sunk wraithlike through the mansion and catches them at the ground.
Goliath and Scarlet Witch are left on the roof to tackle Man-Ape, until his henchman N'Gama winches him up into their flying craft.
Goliath tells Cap who Man-Ape is, a Wakandan named M'Baku who had tried to usurp T'Challa's throne in #62. They had left him crushed by a falling statue.
Meanwhile Panther is visiting Monica Lynne whom he met in #73-74 battling the Sons of the Serpent. Since then she has abandoned her singing career in favour of fighting for black rights. When he leaves her she is abducted by Man-Ape. And Panther wonders whether he should quit the Avengers to join her cause.
When the Avengers bring panther up-to-date with what's been going on, he deduces that N'Gama must have rescued M'Baku and nursed him back to health. But then Man-Ape contacts them and challenges T'Challa to a duel for the life of Monica.
Panther flies up to fight him on board a helicopter of advanced non-Wakandan design. Man-Ape almost wins the fight. But then N'Gama tries to help his boss, and Panther throws him at man-Ape, temporarily stunning him. Panther uses the moment to free Monica, who turns out to be an exploding mannequin.
Man-Ape takes the unconscious Panther, along with the real Monica, to an underground lair. There it transpires that he is a member of a group, the Lethal Legion, led by Grim Reaper. The rest are other Avengers foes Living Laser, Power Man and Swordsman.