We're outside stowny's restaurant in New Jersey. Diana is playing a mom that will leave her baby in the back seat. But don't worry, the baby is a doll. And the crying is just a recording. "What would... See More
We're outside stowny's restaurant in New Jersey. Diana is playing a mom that will leave her baby in the back seat. But don't worry, the baby is a doll. And the crying is just a recording. "What would you do?" Is everything okay? That's my baby. Is she crying again? It's only a few minutes. It doesn't matter. I don't think it's a big deal. It's a baby. It's my baby, and it's not that hot. Reporter: You can see she's visibly shaken and can barely dial the phone number. Are you kidding me? Not a big deal. You're overreacting. Reporter: Ma'am, it's okay. It's okay. Are you all right? I'm so sorry. We just want to show people how dangerous it is. And you showed us. I was really worried for that baby. Oh, my god Reporter: What do you want people to know? If you're lucky enough to have a child, bring them with you. Look at what has happened to so many. It's sad. Reporter: It is sad, but the story is becoming all too common. Another tragic death of an infant left inside a hot car. Reporter: A reality we're forced to face every summer. But not everyone steps up. This man walks by, hears the baby's cries, does nothing. These women, also do nothing. This mother-to-be leaves without saying a word. As soon as this woman gets out of her car, hears the cries. She's angry, but doesn't know what to do. We send over our actress to talk to her. I don't know what she's doing. You can't go to get donuts with your crying baby in the car. You can't do that. Here she comes. I was just grabbing a coffee, what could happen? Anything could happen. I locked the door, no ones going to take her. Ok, that's fine. It's your decision. But I'm just offering you some advice as a fellow parent, that's all. Okay. Have a good day. Reporter: Fed up with Diana, this mother, upset, walks away. She's fine. Reporter: When she returns 20 minutes later, she's had it. I'm going to be right back. This is only going to take one minute. I'm calling 911. Reporter: While she's making that call, we come out to say hello. She's an actress, it's not a real baby. Oh, it's not real? Oh, my god. Reporter: Are you glad you spoke up? I am. Really glad. Reporter: This time, we replace our mom with a dad. This woman immediately calls 911. There's an infant crying in a car with no adult. Reporter: When we send the father in, they quickly let him know what they think. We just called the police. I just went around the corner. It's not a big deal. That's not cool. It takes too long to get the kid out, get out, come back. It's too difficult sometimes. I'm trying to be a good parent, but juggling the things all over the place. Reporter: I'm John Quinones with the TV show "What would you do?" He's an actor. As parents, you were touched and worried. Well, when he's trying to tell me that it's the right thing, you can get upset about it. Reporter: This next couple approaches the car, and are standing by when our dad returns. They' even agree to do some Ba babys babysitting. How long were you going to stick around? As long as it took. Reporter: The baby is still in the car. And while the temperature out side is 77 degrees, it takes just minutes for the temperature inside to exceed 97 degrees. Potentially deadly for a child. This mother and daughter are walking by, listening as the dad returns. I just had to run in for a minute. You can't do that. I was almost going to call the police. Don't ever do that again. I have all the stuff, and it's a pain in the butt. Go open the window for her. But I haven't gotten my sandwich yet, though. That's more important than your child? I cracked the window. I just -- Reporter: She begins to make her way over to a police officer, and we are right behind. Ma'am, how are you? I was like -- Reporter: You know the show? Yes, we do. Oh, my god. Reporter: What do you say to those that say it's none of your business? You don't know this child. Well, nothing is ever someone's business anymore. So, if someone jumps in and does what's right, it will be okay. Coming up --
This transcript has been automatically generated and may not be 100% accurate.