This is a purely science fiction adventure hook. As a matter of fact, it almost solidly lands in the space opera genre.
An unmanned cargo ship from the asteroid belt arrives at Earth’s moon to be offloaded for processing. However, it arrives completely empty. The ship’s logs show that it left with a full load of iron ore and no one docked with the ship between its departure and arrival. Any calls made to the mining operations will result in little information beyond the bewilderment of the shipping company’s employees. The PCs are hired to investigate the mysterious disappearance of millions of dollars of iron ore.
What happened to the cargo? Are the ship’s logs accurate? How did the cargo magically disappear? What will the PCs find in the shipping lanes between the moon and the asteroid belt? If the PCs make it all the way to the belt, what will they find there?