Avengers (1963) #110

The return of Quicksilver! Thor interrupts an Avengers training session to tell the Avengers he received a galactic transmission from Pietro! Turns out Quicksilver was on Attilan, home planet to the Inhumans, where he was nursed back to health by Inhuman princess Crystal. Now, Quicksilver and Crystal are in love and plan to marry. Following this transmission, the Avengers receive an urgent message from the Xavier Institute where the X-Men are in grave danger!