Karen Chisholm
Late in mentioning this one, particularly as I've been reading and re-reading it a couple of times now.
From the Blurb:
Murder, political intrigue, bent cops and the fate of a nation - a thriller set in the murky underworld of 1951 New Zealand.
A man overboard, a murder and a lot of loose ends ...
In Auckland 1951 the workers and the government are heading for bloody confrontation and the waterfront is the frontline. But this is a war with more than two sides and nothing is what it seems.