During the Nazi occupation, Amsterdam family banker Walraven van Hall enthusiastically accepts, despite brother-partner Gijs and many colleagues' reservations, to help the resistance by financing them with fake credits, for which the Dutch government in exile gives a post-war guarantee. As the war drags on, he largely exceeds the guaranteed sum and forges a coordination between resistance components, but the Germans plus collaborators set up a large operation to find and roll up the 'underground bank'. As Allied forces approach, a far larger sum is needed to pay for a massive railway strike, but the regular systems are exhausted. Walraven now devises a daring plan to liberate funds from the national bank by a complex web of forged promissory notes, but the ruthless SS is hot on their trail.