The scientists scour many worlds until they find one that fits the prince's requirements--an earth where medicine had advanced considerably beyond their own. Luckily, they also find a husband-wife team of brain surgeons who are world renowned in the field.
The prince orders them abducted and brought to him. When they meet, he showers the surgeons with expensive gifts and great riches, which they acceptin return for curing his father. Then, to their chagrin, they discover that they will never be able to return to their own world because the time machine had been destroyed.
Being exteremely hardy people they accept their fate and undergo numerous adventures, some of them quite dangerous, as they establish themselves in their new reality.