Best book ever, in my opinion. I had zero interest in firefighters or smoke-jumpers and this book took me full tilt into the subject, which remains to this day.
Maclean's writing style is unique, mixing poetic prose with science - he spent his dotage trying to solve the mystery of what happened with the Mann Gulch fire, from its start to its end. His goal was not just to provide answers, but to ensure that the dear young men who perished very cruelly as the fire pursued them up the steep ground of Mann Gulch were not forgotten or ignored in death.
I'm a huge reader and if I had to take only one book to a desert island, it would be this one. I've read it dozens of times and learn something new each time. It's a complex book that requires time and attention, not skimming; the volume of science in it can be challenging and my advice would be 'go slow, re-read each chapter twice'.
Maclean passed away before it was completed, however others pulled all his work together and finished it. It does not impair the work at all.