The Untold Legend of the Batman #1 (1980)

In the Batcave, Batman opens a package that came in his mail and finds within it the shredded remains of Thomas Wayne's Batman Costume which he wore to the party that ended in his encounter with gangster Lew Moxon. Batman rushes to the display case where the costume had hung and finds only a note taped to the inside of the glass with a threat addressed to him. Grimly, Batman recalls to Alfred and to himself the night that his father went to the costume party dressed as a "Bat-Man", was abducted by thugs to treat the wounded Lew Moxon, and wound up capturing them all. He goes on to remember Moxon's emergence from jail ten years later, and, soon after, the murder of Thomas and Martha Wayne by Joe Chill; Bruce Wayne's determination to fight crime and bring his parents' killer to justice; his becoming the first "Robin" and teaming up with detective Harvey Harris; his attending Gotham College, where he learned the difference between law and justice from Professor Amos Rexford; the bat that flew in through the open window of Wayne Manor and inspired him to become the Batman; the many battles he and Robin waged against an army of criminals; and the deaths of Joe Chill and Lew Moxon. Batman learns little from analyzing the shredded costume and thus, he heads out on patrol of Gotham City in the Batmobile, on a mission of vengeance.