"What this trial is really about is money and lots of it," McColgan said.
Gan, a mother of three, ran a business importing food from China to the Pacific Islands when she "cottoned on to an almost perfect way" of importing drugs into New Zealand.
It revolved around a process known as "trans shipping", where items transported from one country and destined for another are briefly held in a Customs-controlled warehouse in New Zealand on the way.
Gan allegedly had "an inside man" who could access those restricted holding zones.
In October 2013, McColgan said the man drove into a warehouse, withdrew 250kg of ContacNT from the defendant's shipment and replaced it with the exact same weight of potato starch.
The goods had come from China and were on their way to Tonga.
"It was almost the perfect scam," the prosecutor said.
But "perhaps unluckily for Ms Gan" her alleged co-conspirators were police suspects and had been under surveillance for some months.
McColgan said the police investigation, complete with intercepted communications, showed clandestine meetings and coded messages between the defendant and her associates.
He also highlighted the fact she had bought a new phone in the days before the ContacNT had arrived in the country and disposed with it only days after it was removed. The jury was asked to question: "Is that normal? Is that usual? Is that legitimate?"
"It suggests something very untoward going on here," McColgan said.
After police financial analysts probed Gan and her husband's bank accounts they found several "vast, unexplained cash deposits".
It is alleged they coincided with Gan's other international shipments which had passed through Auckland, which led to her facing two other counts of importation.
While the defendant never physically touched the drugs, McColgan said she exercised control over their movement and that was all that was needed to prove the charge.
The trial before Justice Mathew Downs and a jury of six women and six men is scheduled to last two weeks.
