The Dutch East India Treasure is a collection of wealth that was intended to be given to France, but was instead stolen by pirates.
Captain Lawrence of the Heerlijkheid said he had the treasure on his vessel, but never gave to the people of Skipbrot. When the ship crashed into the Icelandic town in 1783 following the eruption of Mount Laki, he had promised the town the treasure, but was killed when he never followed through with it. It had remained a legend ever since.
Soren Bergursson, a historian running Skipbrot's Cultural Center, wrote on his tablet in 2015 about how King Louis XVI of France appointed a new financial comptroller in 1782 in the midst of the first American Revolutionary War, which France was participating in. The country was heavily financially drained, so Soren suspected that extra money might have been stockpiled away in case it was desperately needed. He believes that the Dutch East India Company was to deliver this treasure on the Heerlijkheid, but since it crashed in Iceland and never made it to France, the country was bankrupt and the French Revolution happened. As such, it changed history and the discovery of the treasure would be quite big.
When looking for Magnus Kiljansson after he goes missing, Nancy discovers Captain Lawrence's journal in which he reveals that the Heerlijkheid was indeed stolen just north of Cape Town, and his men realized that the treasure was far too great to sail back to England with where it could easily be taken again. They hid it in an ice cave near Skipbrot, intending to go back to it later when it was safe, but they never did.
Nancy discovers that Soren had kidnapped Magnus out of desperation to find the treasure. Nancy finishes putting together the clues Lawrence left behind and finds Magnus and the treasure. She finds out that a fake treasure was also hidden to throw off pursuers and lets Soren have the fake treasure when he is threatening her. Nancy finds the real treasure and it is given to Magnus and Dagny, his business partner.