Triangle 1992-42. Continued from Superman: The Man of Steel #17 and continues in Adventures of Superman (1987) #496.
After finishing a mission with the JLA Superman is approached by Liri Lee, asking if he's seen Waverider. When asked why, the member of the Linear Men is characteristically vague.
Later that night while on a dinner date with Lois, Lana, and Pete time comes to a halt just as a man at the next table is having a massive heart attack - only Clark seems aware that time has stopped. Waverider suddenly appears and it is revealed that the dying man was his grandfather.
Stricken by grief, Waverider pulls the Man of Steel with him to the Linear Men's base of operations at Vanishing Pint to confront them for drawing him to the scene of his loss for their own gain. As the confrontation grows more tense, Waverider blasts the leader of the Linear Men with a bolt of temporal energy killing him on the spot. With the leader dead all are drawn into a null sphere outside of time with no past or future - who was the leader and how could his death have such an impact on one who is a living part of the timestream itself?
Elsewhere: Doomsday's escape from his tomb proceeds as the monster makes the first cracks in the cell wall.