In writer Jason Aaron and artist David Marquez's Avengers #9, Namor returns to his roots as a surface-hating villain, declaring war on the Avengers and everyone else on the surface.
To find out the motivations for Namor's turn - and the extent of the havoc he wreaks - read on.
Spoilers ahead for Avengers #9.
Avengers #9 kicks off with a new round of the aquatic grudge match between C-list villain Tigershark and former Avenger Stingray. As the pair clash, Namor interrupts them, demanding their allegiance in his fight against the surface world.
Stingray refuses, leading Namor to beat him mercilessly, destroying his underwater suit and leaving him to be eaten by "war sharks."
Seeing what happens to those who refuse him, Tiger Shark joins Namor.
Later, the Avengers confront Namor in the wreckage of Atlantis to recover human operatives of Roxxon who Namor captured after they killed Atlanteans and desecrated their bodies. After speaking with Captain America and elucidating his grievances, Namor agrees to let the Avengers leave, but will not give them the humans.
The Avengers manage to recover the prisoners when Namor is distracted by Atlantean children, who flee him - but not before he banishes Steve Rogers from Atlantis and declares war on the surface world.
Later, as Namor lists the ways the surface world has harmed Atlantis - the murder of Atlanteans by Roxxon, Atlantis destroyed by a sunken Celestial, Atlantean children left to die on the beach by humans - Namor uses seawater to drown the Roxxon agents by flooding their cells on the surface world.
It's revealed he's speaking to his own team of underwater villains - the Defenders of the Deep.
During New York Comic Con, Marvel unveiled a new Invaders series debuting in January, which will juxtapose Steve Rogers and Namor's time as friends in World War II and as enemies in the present day. It seems the seeds of that story have been planted here.
The story continues in November 14's Avengers #10.