What if your close friend/close acquaintance was a serial killer? A brutal serial killer? You'd probably express shock and disbelief until the evidence convinced you (or failed to convince you). And what if you were a crime writer, contracted to write about those serial killings? The Stranger Beside Me would be the result.
This true crime story is different because the author, Ann Rule has a personal stake - she once worked with Ted Bundy at a crisis hotline, and they kept what she called a close, if sporadic friendship. So parts of the book include her experience working with Ted, and her involvement in his trial (she wasn't a witness, but he did call her and stuff).
If you haven't heard of Ted Bundy, he's the one who killed a bunch of girls (brutally killed/mutilated) and almost got away. In fact, if it weren't for the fact that he ran away, and made a bunch of extremely stupid mistakes (like running to a state with the death penalty and representing himself), he would have actually been a free man by now (probably), or at the very least, alive.
Since Ann Rule knew Ted Bundy, part of the book wonders at what might have happened. What if someone intervened? What if he wasn't given to such deviancy? And since her theory is that each kill was an expression of the fantasy of revenge on this girl that dumped him, what would happened if his first girlfriend didn't dump him? By all accounts, he was extremely bright and could be very motivated.
Personally, I'm glad that he was caught and sentenced to death. From the book, and the wikipedia article (the book didn't include some theories), it seemed like Ted Bundy couldn't be reformed.
An interesting true-crime book, worth reading if you have an interest in such stuff.