The explanation in the book wasn't very helpful either. It just showed black 1 and pointed out that A and B were miai for two eyes. Again, I checked on the board. Again, black died on me. So I went to preparing the diagrams about the evil evil book that presents you with a wrong tsumego, wasting your time in doing so.
And then ... I got it.
Have fun trying to solve it yourself before expanding the post ;)
Black to live!
So the very first point coming to my mind was P19 making A and B miai for two eyes. That happens to be the right answer. My concern were the cutting points at Q18 and R17. I was afraid of being mislead to a wrong answer and wanted to make sure I did not miss something. So I kept on reading.
And ... I was right (in a way). There was a trap for black. White 4 gives atari. If black connects at A, white takes the whole group down at B. Ergo: Black can not connect. Ergo: White connects to the outside group and destroys black's eye. Ergo: Black is dead. Ergo: Black 1 is the wrong move. And off I went looking for another answer. I guess it won't surprise anyone that I did not find one.
I will add some white space so that you can look for the solution from diagram 2. I think it is fairly easy, if one starts from this point. The task, of course, is still the same: Black to live.
Scroll down for the solution.
Black plays on 5.
Aaaaaaaaaaaand ... it is a snap back. Black simply retakes at A.
I feel stupid now :D Especially because I was proud that I start to see the snap back quite easily (I had real difficulties with it for quite some time and I'm glad they are almost gone). I just was not able to read that one out from the beginning. Which saddens me a bit. I need to question my abilities more than the book. If I had tried to go one step further, I might have solved it. In which case I would surely have written about that tsumego as well - only that I would have bragged about me solving it like crazy ;)
Good night, and good luck!