Facing Ethical Dilemmas, What Would You Do?

Suppose you saw a friend's spouse cheating, would you tell her? What if you saw a young girl being cruelly taunted by other girls, would you confront them?

Using hidden cameras, "Primetime: What Would You Do?" sets up everyday scenarios and then captures people's reactions. Whether people are compelled to act or mind their own business, John Quiñones reports on their split-second — and often surprising — decision-making process. This series looks at what people actually do in difficult situations, not what they say they would do. How they act in the face of dilemmas is a test of their character and values.

"Primetime: What Would You Do?" premieres Feb. 26 at 10 p.m. ET.

On Friday at 10 p.m. on "20/20": We wanted to know if anyone would step in and try to stop teens blatantly vandalizing someone's private property in a suburban parking lot.

ABC News hired teenage actors to vandalize a stunt car, set up our hidden cameras and watched as people passed by, stepped up or got steamed. But before our experiment was over, we got a startling lesson in human nature — a lesson that may shock you.

And, what if you were dining at a fancy restaurant when suddenly, across the room, you saw your good friend's boyfriend canoodling with a complete stranger. Would you tell your friend? We recruited six couples: two of them married, two engaged, one with a baby on the way and all of them in committed relationships. We asked them to pretend to cheat on their mate in front of an unsuspecting best friend. Our hidden cameras caught reactions you won't want to miss.

Tune in to "20/20" Friday for this sneak preview and Feb. 26 on the premiere we'll have the following scenarios:

Based on the real-life experiences of a devout Muslim woman living in west Texas, "Primetime" finds out what happens when a Muslim woman wearing a veil is denied service in a popular bakery by the owner. Who will come to her defense and who will support the owner who wants to kick her out? The situation draws several emotionally charged reactions.

Adolescence is tough and teens can be cruel, bullies even. But while bullying may be associated with boys, girls can be bullies too. Girls tend to assault their victims verbally, causing deeper, hidden wounds that can last longer than any playground punch. When "Primetime" creates a scenario where three girls verbally attack another girl in a park what will people do when they walk by? Viewers see how the situation clearly touches a nerve still raw for women of many different ages.

Finding a parking space is a common inconvenience for many people that often can be compounded by the only spot available being too small for the car. But what happens when "Primetime's" parker bulldozes her way into the tight spot, trashing the cars in front and behind. Does anyone intervene to prevent the damage?