Come up with a plan to circumvent that security. It’s being held some place under heavy security. Heists aren’t limited to cash robberies: You need a thing (document, artifact, maybe even a person). Heists are a fantastic scenario structure for a GM to have in their pocket. Once the crew is recruited, over the course of the rest of the film we see them plan the heist, cope with a number of unexpected complications which disrupt their plans, and then execute the heist. Danny Ocean puts together a crew of eleven criminals to simultaneously rob three Las Vegas casinos owned by Terry Benedict.
So instead I’ve shifted my attention to a different target: Ocean’s 11.
(The only thing I really came up with that seemed to have a chance of working well also featured such a massive amount of over-prep / wasted prep that I couldn’t reasonably recommend that anyone actually use it.) I was hoping the next installment of the scenario structure challenge would feature a battlefield scenario structure, but what I did instead was beat my head against a wall for six months failing to come up with a structure that made sense.