Summary
Other reviewers are correct: you do need to purchase some of the original comics of Knightquest to find out what happens in between the end of Knightfall and this story. Alternatively, there are novelizations by Dennis O'Neill and Alan Grant you could read. In short, Bruce's back heals and intends to retire to his civilian life, but Robin informs him of Azrael's violence as Batman. Bruce then vows to reclaim the mantle of the Bat, apparently scaring Alfred (his longtime butler) away because he fears Bruce will be seriously injured again. In our real-time, Alfred doesn't return for over a year. Azrael 'shoves' Bruce away when he returns to the Batcave, and Bruce realizes that he must go into training if he is to have any chance of defeating Azrael.
The story itself picks up at the beginning of Bruce's training to restore his physical strength and instincts. The writing is psychologically intense, and the fight scenes are mostly fun entertainment that would not be out of place on the 1960s TV series.
In the end, we see all that makes the Batman great and everlasting. A fitting close to arguably the biggest Bat-story ever done to that point.