I found that at times the story lines in "Sub-Zero "meant you had to stretch your imagination a bit & that they were a little surreal.
I enjoyed it as part of the continuation of the "Submariner Sinclair " series, which is why I give it three stars, but I think if I had read it as a 'Standalone ' book I would probably only give it two & any reader should take this into consideration. The series as whole is good, but this book (in my opinion) is not one of the authors best.