Wartime Auckland: German raiders hunt merchant shipping in the Tasman Sea. A Japanese pilot flies a daring predawn reconnaissance flight over the Waitemata Harbour, as Aucklanders sleep, blissfully unaware, below.
And on a cliff high above Piha, men and women at a hastily built radar station scan their screens for a tell-tale ''sausage'' blip that could indicate an approaching enemy aircraft or submarine.
Seventy years on, some believe they may have given warnings of enemy raids but still can't be sure. The truth is lost in a fog of wartime secrecy, limited understanding of the brand-new technology and, according to local historian Sandra Coney, a bit of old-fashioned sexism against the mainly female radar operators.
''You can imagine it, can't you?'' says the Auckland councillor and journalist, who has recently had her book On the Radar: The Story of Piha's World War 2 Radar Station published.
''Because it was new technology, even the top brass didn't appreciate the power it had. And then you've got this added thing that the women weren't seen as competent with this scientific and technological advance, and therefore, when they were picking up something, they were not believed.''
Coney first discovered the stories behind the radar station, which used to sit on the hill above her parents' bach, when she wrote a history of Piha in 1997.
The result of her fascination is a highly personal book, which combines the little-known story of New Zealand's coastal defences in World War 2 with her own local knowledge of how the station transformed the sleepy seaside village of Piha.
Quirky anecdotes abound, such as the time her father, Tom Pearce, who ran the surf club, was mistaken for a submarine conning tower as he stood at the sweep of a surf boat coming in to Muriwai.
Coney describes how New Zealand got a flying start in the development of radar, as the DSIR's top scientist, Ernest Marsden, was in Britain for a secret briefing on the new technology when war broke out.
He returned to New Zealand by ship with locked crates containing the basic components, including television sets for the cathode ray tubes used to project radar signals on to a screen.
Unfortunately the air force at the time saw little potential in the technology, so Marsden and the DSIR set up their own secret laboratories in Wellington and Christchurch.
This led to the establishment in 1942 of six coastal monitoring stations around the upper North Island, including Radar Unit Number 4 on Hikurangi, an imposing hill at the south end of Piha Beach with sweeping views across the Tasman.
Unusually for wartime, it was staffed by a combination of men and women from the air force and navy.
All the radar mechanics were men but following Britain's lead, most of the radar operators were women, apparently because women were considered better at sitting still and concentrating.
The WAAF (Women's Auxiliary Air Force) operators worked two at a time in a blacked-out room, studying the cathode ray tubes in a giant steel cabinet receiver for telltale blips which could indicate an echo.
It took skill because the echo could be an aircraft or ship or just background noise from a nearby headland or pods of whales.
They plotted their findings on backlit maps and phoned them in to the Filter Room, a secret coastal defence nerve centre based at the Auckland Teachers' Training College in Epsom and copied directly from the British model which played a vital role in the Battle of Britain.
Plotters, armed with poles, shifted planes and ships around on a giant map on a table, based on incoming reports from radar stations. Filterers decided when the often-conflicting information was reliable enough to form a track.
The controller, who knew where Allied ships and aircraft were supposed to be, had to make the crucial call on whether to scramble fighter plans to intercept the enemy.
As Coney puts it, the scenario might sound fanciful today but for New Zealanders in the depths of wartime, the fear of attack was very real.
''I remember my parents talking about things like hanging up of the blankets in the window so there were no lights shining out to sea for the German submarines or the Japanese invaders.
''Unless you lived through it I don't think you can appreciate how directly threatened people felt. Boats being blown up in the Hauraki Gulf, a whole series of things that made people feel it was very close ...''
Post-war records show just how near the Germans and Japanese came. In June 1940, the German raider Orion (a converted merchant ship with concealed armaments) laid mines in the outer Hauraki Gulf that sank the transpacific passenger liner Niagara, fortunately with no loss of life.
In August, the Orion sank the steamship Turakina on its way from Sydney to Wellington, firing torpedoes as the captain valiantly fought back with a single gun at the stern.
And in January 1945, U-boat captain Heinrich Timm took his vessel into Gisborne harbour, where he was amazed to find the whole town was lit up ''like Christmas''. The following night in Napier Timm brought his crew up on deck to watch the local people partying.
The Japanese, considered the greater threat, had reconnaissance planes that could be assembled on the decks of submarines and packed away again after use.
The book describes how in the early hours of May 24, 1942, a Japanese submarine surfaced at Mayor Island near Tauranga and launched a float plane.
The pilot, Susumu Ito, flew over the Coromandel and the Hauraki Gulf islands before swooping low over Auckland's wharves and the Devonport naval base, looking for British or US naval ships for Japan's midget submarines to attack with torpedoes.
Fortunately for the Allies none were in port at the time, as Ito made a similar flight over Sydney Harbour a few days later, probably providing information for the midget submarine attack that sank the HMAS Kuttabul, killing 21 Australian sailors on board.
Coney says it's difficult to tell how effective the radar stations were in detecting such attacks, as most operational records have been destroyed and everyone involved was sworn to secrecy for 50 years - meaning most have now died.
However, she says there are several stories of Japanese flights over Auckland that were detected by radar but the reports were not believed.
One comes from her Auckland Council colleague Richard Northey, whose mother was one of the WAAFs in the Epsom Filter Room. Althea Cornes told him that the radar operators at Piha detected a Japanese plane flying over.
''They relayed it to Althea at the Filter Room but when she told her superiors, they reacted with: `Silly woman, it's obviously just a plane that has forgotten to activate its sensor'.''
Some confusion was understandable, as American pilots heading to New Zealand from the Pacific frequently forgot to switch on their IFF (Identification Friend or Foe) equipment, which revealed they were friendly aircraft. The mistakes caused panic in the Filter Room but usually turned out to be false alarms.
However, Coney says the anecdote is backed up by the official history of the RNZAF, which shows at least one radar report of enemy activity was wrongly dismissed by military bosses.
Former radar mechanic Ian Sexton, now 92, is also convinced he spotted a submarine travelling ''faster than any fishing boat'' while working at the Maunganui Bluff unit in December 1942.
''They didn't want to know at headquarters. The older people didn't seem to understand what radar could do and the senior officers, of course, were all older people.''
The book also reveals the social side of life at the Piha station, which radar mechanic Henry ''Angie'' Angelini described as a bit like a holiday camp.
''They were all healthy young people and there was a vibrant social life, especially in the summer months,'' says Coney.
''They had their amusements (at the station) with the ping-pong table and the gramophone but there was a lot more going on down at Piha village, including more people of the opposite sex.''
Did romance blossom then? She's sure it did but even after 70 years it seems it's bad form for the men and women still alive to talk about it. Some wartime secrets will go to the grave.
The book
On The Radar: The Story of Piha's World War 2 Radar Station, by Sandra Coney (Keyhole Press and Protect Piha Heritage). Available from www.piha.co.nz/books.
