“This is your last chance to change your mind. We are about to pass the point of no return.”

The point of no return is a place where, if you go any further, you will not be able to go back. For example, if you have fuel or supplies for a ten-day journey, if you travel away from town for more than five days, you won’t have enough fuel or supplies to get back to the city if you give up on your goal. It can also be used when you cannot go out the same way you came in, such as because the door locks behind you or you go down a steep cliff you can’t climb back up.