Gathered together by telepath Professor Charles Xavier, The X-Men are sworn to protect a world that fears and hates them.
Now one of their number - the winged mutant known as Angel - is missing! Weakened by their battle with the drooling alien Brood, his comrades must descend to the darkest nether reaches of the city. Here, they encounter a mysterious underground race known as the Morlocks. Battling a menace they cannot defeat, it appears that these dark catacombs may well become the final resting place of The Uncanny X-Men.
Collects Uncanny X-Men(1981) #167-173. Printed in black and white.
— Description from Comic Vine community (comicvine.gamespot.com).