A Gift From Earth by Larry Niven
This is one of those starship crew vs. colonist passengers stories. Slower than light ships brought colonists to a planet that is mostly uninhabitable. Only the large plateau area "Mt. Lookit That" provides a livable environment. The former ship crew runs the colony with the descendents of the non-crew as a lower caste. Criminals and rebels are used as a source for organ transplants to extend the lives of the upper caste and select other individuals. The number of available organs is limited and the crew control access to them. This and other control over medical care is an element in maintaining power over the population.
Centuries later, an unmanned slow ship from Earth arrives. This one carries scientific information on artificial organs. The potential of an unlimited supply of replacements for organs is a threat to the established order. Rebels would like to get the information. The task becomes dependent on one rebel, Matt, who has some capability to make people not notice him - which serves the same purpose as invisibility.
For younger readers who are open to stories about youths with (more or less) super-powers, this could be an entertaining tale of rebellion.