X-Men, Vol. 5: War Machines

When a sinkhole appears under mysterious circumstances in the middle of the Black Rock Desert, the X-Men go to investigate... But little do they suspect that the phenomenon has connections to old allies, and enemies! Then, trapped deep underground in the sinkhole, Storm battles her claustrophobia while trying to find answers. Meanwhile, her teammates above ground discover that the phenomenon has ties to old enemies. Collecting X-Men (2012) #23-26.