Transcript for GPS Astray: Lost in Death Valley
Highway confidential. Here is david muir and elizabeth var guess. Good evening. Texting to their own de tonight, here it's not the only technology that can lead to danger behind the wheel. That's right. Even when you think you're in good hands, like with a gps. It gets you where you're going, right? Well, not always. Jay hits the road to retrace is journey that was hell on wheels for one family. Lost in the hottest place on ert. The very thing they were counting on them to save them, didn't. Their gps. ♪ Reporter: Inside the little grey hyundai sailing along with "hotel california" playing on the radio is donna cooper. Donna, her daughter gina and their friend jenny leeung visiting from hong kong are on a day trip to an old mansion-turned tourist museum in death valley. I had never been to scotty's castle. I'd been saying for years I'd like to go, but I never went. It's a nice day trip. Reporter: They recently came back to death valley and relieved the memories. What was the day like? Beautiful, gorgeous. Hot. Hot. Reporter: So it was a good Yeah. Turn left on california 190. Reporter: Also along for the ride, donna's trusty gps, nicknamed nell. I named her after my mother who was always telling me how to do things and where to go. Reporter: That's perfect. Their other -- more ominous -- travelling companion today is the weather. Outside their climate controlled car, nature is in control. Death valley's staggering beauty is matched by its deadly heat. It's the hottest place on earth. On this day, the temperature will reach 121 degrees. Park rangers know what that can mean -- for somebody stuck in the back country without water, they will begin becoming disoriented, dehydrated. Kidneys will shut down. Blood starts to thicken. Stroke, coma and death. Reporter: But all that could not be further from the minds of donna and the girls. What did you take in terms of provisions? We took some food, some water. It's more than enough for a day trip. Reporter: Their decision to visit that popular tourist museum was so spur-of-the moment, no one knew they were going. Not even donna's husband, roger. He's in florida tending to their other daughter, sky, who is undergoing gallbladder surgery. Did she mention that she was going to go out to death valley? No, but she did tell me to have sky call her when she came out of the hospital. You know, just to find out how she was, make sure she was okay. Reporter: At 1:00, the women arrive at the museum. Two hours later, on their way out, donna stops at the gift shop to buy gina a t-shirt. She swipes her credit card, and they set off for home. We just headed on the road the same way we came. Reporter: Except for one small, fateful detour. And then we saw a sign about the racetrack, and I'd never seen it, and I've always wanted to see it. It's very interesting. Reporter: The racetrack is a geological curiosity. Shifting boulders leave skid marks in the cracked mud. But to get there, you need to go off the paved highway onto jagged back roads. We drove for, like, ten miles, I would say. And never saw the racetrack. Never really saw anything. Reporter: Turning around, the women come to teakettle junction -- a dirt intersection where a number of unmarked roads cross. Here is where their day trip begins to turn into a very bad trip. At the end of that ten miles, we weren't back where we began. That's when I said, well, we went the wrong way. Let's put the gps on and get back on the right road. Drive.8 miles on dirt road on left. Reporter: Nell begins dispatching directions with the confidence of a digital brain. Turn 2.1 miles to sb intersection on the right. We were kind of, like, getting aggravated with -- with nell, because she was, like, taking us nowhere. Reporter: Getting lost like this in death valley has a nasty history. Legend has it the park got its name during the california gold rush when treasure seekers discovered the valley was a shortcut to the gold and the undertaker. But gps has added a cruel twist to the old tale. In 2009, a 6-year-old boy died after his mother became lost following her gps. As I learned more about that case, I found out that they had went down a road that no longer existed. Reporter: Ranger charlie callahan says growing numbers of visitors to these remote areas are being put at risk by devices with directions that are misleading or plain wrong. If you're asking to go home, but if you're not saying lead me to the closest paved road, just the shortest route, that gps could lead you, you know, through a hundred miles of dirt road before you reach the paved road. Reporter: Though charlie's been working with gps manufacturers to improve their databases, a quick test we performed confirmed there are still major problems, either because of outdated maps or a device that hasn't been updated. Then turn right on the road. Reporter: For example, the directions to golden canyon road couldn't be clearer. This seems pretty straightforward. This is a good paved highway. Turn right on golden canyon road. Reporter: But where the gps says there's road -- I don't see a road. What we have is a canyon wall. Oh, definitely. The road used to go a mile in here but that washed out in 1976 in a flash flood. So this road has not existed for 35 years. Reporter: Whether something like this is happening to donna and the girls is unclear. But it's unmistakable that instead of heading home, they are moving deeper into desolation of death valley. Drive.8 miles to teakettle. Recalculating. Recalculating. It just kept saying, you know, go this distance and take a turn, go this distance and make a u-turn. There is nothing there. Reporter: The gps is confusing, and their cell phones are useless. Back in florida, roger and sky's calls aren't being answered. Sky tried to call her just got voicemail. And it was a minor concern. It wasn't a major concern at that point. Reporter: It should have been. Death valley's vast featureless landscape is disorientating the women. No landmarks. There's no people. There's no houses. There's no cars. There's no animals. We didn't even see an ant. Reporter: The temperature is now peaking at 121. And their provisions are vanishing. A half a bottle of water left, and a quarter tank of gas. And then, in the middle of all this immense emptiness, a curious sign of hope. And straight out of the clear blue sky, there's these. This row of mailboxes. Mailboxes! There's not a soul. There's not a -- any sign of civilization. So, I got out, opened them, and one of them mailboxes there's a piece of yellow paper. Yellow paper. Saying that, sorry we have missed you. Come by again. We were under the big tree, whatever big tree means. Reporter: It's lost. So we put it back in the mailbox, and we kept going. Reporter: Now the light -- and their mood -- grows dimmer. The gas tank light flashes on like an exclamation point, and the car spits and sputters to a stop. We were out of gas. We were out of road. We were out of everything. Reporter: Tonight, they remain lost. But tomorrow -- stripped of their air conditioned cocoon -- will be deadly. Their salvation down to a prayer and a clue they shut the door on a few miles back.
This transcript has been automatically generated and may not be 100% accurate.