This book takes place in the universe created by Larry Niven, the one populated by Kzin, Humans, Puppeteers, and the like. The story takes place during the first Human-Kzin wars, and follows the journey of two human soldiers, Carol and Bruno, during and after their attempt at a suicide mission to destroy the Kzin homeworld. After being found by Kzin warships, they all attract the attention of the Outsiders, the race of creatures who live at just above zero kelvins. The warring factions are drawn together by a threat greater than the two pose each other, as the author explains the reason behind the existence of the Outsiders and more.
If you liked Larry Niven's "Ringworld", then you would likely also enjoy this book. I'm not sure if it was with Larry Niven's permission that this book was written, but it follows well, and exposes a few things that people enamoured with the Ringworld and Man/Kzin universe will like to know.