Avengers (1963 1st Series) #141

"The Phantom Empire!" Part 1 of 7. Script by Steve Englehart. Pencils by George Perez (first work on the Avengers). Inks by Vince Colletta. Cover by Gil Kane and John Romita. 

Captain America returns to Avengers Mansion seeking help in his ongoing struggle against the Brand Corporation and Roxxon Oil. However, the Avengers already have a crisis on their hands with the confirmation of Hawkeye's disappearance...and the high probability of Kang the Conqueror's involvement!