Thanks for starting this thread, and for the map, @ColyH !I haven't seen a thread for this but it's a very strange case. To summarize a man in was in his car that was broken down and witnessed a car being followed by a pickup truck. After awhile the man realized no help was coming and began walking back to a store he had passed and came up to the car he had seen earlier. The car was completely abandoned so he kept on walking. Months later four of the five bodies were found but no one has ever figured out why they left their car and what caused them to wander so far away. There is more to the story at the link I have posted below.
'Bizarre as Hell': The Disappearance of the Yuba County Five