"Sub-Mariner Joins the Evil Mutants"
Reprinted from X-Men (1963) #6.
Professor X rightly suspects that Namor might be a mutant, and decides to seek him out. The Professor isn't the only one, as Magneto seeks to recruit the Sub-Mariner for the Brotherhood of Evil Mutants.
Namor is intrigued by Magneto's offer of partnership, and goes to parlay, arriving just before the X-Men raid Magneto's island strong-hold. Namor soon feels like a pawn in the conflict, and departs, destroying Magneto's base. Magneto and the Brotherhood escape in the commotion.
22 pages (X-706).
Includes pin-up of original cover.