it's a stupid choice to get kidnapped if you're an adult. yes, its a choice. a child wouldn't know better, but you can't coerce a smart adult to go with you. if someone tried to get me to go in their car and point a gun to my head, they have worse things planned then death. so at that point, you either take your chances of dying quickly or go through something horrible thats worse than dying quickly. you choose to get into the car. its never not a choice to go somewhere. its stupid to go with someone somewhere when they're probably a sadistic serial killer that wants something worse than death. very dumb choice.
Handy dandy device and easy to hide on your person if necessary. Should such a situation arise, take both out at the same time. If buddy runs, throw your loaded gem in their direction and run the opposite way. Either way, it will be death for one or both. Preferably the other one, but you will increase the odds of your own survival.