All-Star Comics #29

Johnny takes an interest in a disheveled man that enters a diner, and buys him dinner. In gratitude, the man says he was born in 2414, a time of perpetual peace and quiet, which bored Landor, so he uses an old time machine to travel back to 1946, but is trapped when the machine disintegrates. Johnny is skeptical, but when a prediction of Landor's occurs, the JSA accepts Landor's challenge to them: the present knowledge of science versus the future knowledge of science. Wonder Woman writes down the six locations where Landor will strike, and the members get their assignments and head out.