Synopsis for “Suddenly…the Sub-Mariner!”
The Scarlet Witch collapses after the battle in the previous issue. Black Widow steals an experimental jet from General Ross. Meanwhile, the Sub-Mariner attacks a submarine destroying underwater wildlife, then decides to attack the base it came from. The Avengers receive a call from Captain America, warning that a dangerous item called the “Cosmic Cube” has been spotted near the base and the Avengers should secure it. Quicksilver stays with the weak Scarlet Witch and the Avengers arrive at the base and battle with Sub-Mariner, where Hercules unwittingly mentions the cube to him. The Sub-Mariner flees, returns with the cube and the battle starts again. He is beaten again however, when he loses contact with the cube, and it is lost down a crack in the ground which seals itself after. The Mole Man finds the cube, but throws it away, dismissing it for a useless bauble.