Adventures of Superman #523 (DC, 1995 — Cover A)

Part 2 of the 7-part "The Death of Clark Kent," continued from Superman #100 (1987): With those close to Clark Kent in mortal danger from the villain who's discovered his double identity, Superman becomes torn between protecting his parents and checking on Lois. And when the Man of Steel tries to contact her... there's no answer. Continued in Action Comics #710 (1938).