Sub-Mariner #36 by Sal Buscema and the Very Great Bernie Wrightson!

Seeking an undersea ally, Namor makes his way to the undersea realm of Lemuria; Namor meets Llyra, the empress of Lemuria, who has overthrown Karthon; She tells him of her origin in hopes of persuading him to join her conquest of the sea; Namor wants nothing to do with it and is caught off guard and captured; Namor meets Llyra's sister, Laurie, who frees him; Namor battles with the sea creatures Llyra can control and their battle ends in her death; However, Llyra changes back to Laurie and he realized that they both shared one body; Namor meets her mother and learns that it was her that had actually freed him.