Based on fact, extrapolated into a fictitious mission this novel involves the Japanese underground military fortress of Rabaul, New Guinea (more specifically, New Britain). Whilst such a place did exist, the mission in this novel never did. In real life the fortress of Rabaul remained unconquered and stood until September 1945, after Hiroshima & Nagasaki, that the commander of Rabaul surrendered to allied forces.
The story itself involves a plot to smuggle explosives into the fortress and set off the simmering volcano of Matupi. Like all good war stories things go wrong; there's a nice mix of complications, changes and betrayal. Not so much that it's tiresome, but enough to maintain the feeling of adventure and desperation without being 'hollywood'.
Quite an enjoyable read, although does paint the Japanese forces in a rather dim light (some may say reasonably so).