I was in Chicago last month for a quick family vacation staying at an Airbnb a few blocks from Navy Pier. I was walking to a Target for a quick errand when a paper airplane fell from the sky and landed at my feet.

On each wing, scribbled in pencil, a message: “Open me.”

Clearly, this paper airplane hadn’t taken flight on its own. (That would be one hell of a paper airplane if it had.) So, I looked up, expecting to see youths hanging over a balcony from the high-rise apartment above, waiting to see how I would respond. No such luck. Whoever fashioned this paper airplane was good — real good.

That said, I wasn’t going to be some schmuck at the center of someone’s prank, caught on camera bewildered by a paper airplane for all of Instagram to see.

I kept walking past the paper airplane, ignoring its simple plea, until I reached the intersection a few paces away. Seconds passed while I waited at the light to cross, and I began to think about what was at stake.

I thought:

Maybe it’s a message for help.

I’m in Chicago — no one knows me here. What does it matter if I make a fool of myself? 

Maybe I can go back and open the airplane and react as little as possible to whatever I find.

Maybe it’s filled with white powder, and I’ll be left retching in the streets like an extra from “The Walking Dead.”

Maybe I’m under-slept, it didn’t actually fall from the sky, it’s just trash left on the sidewalk, and I could throw it away after opening and make it look completely casual if not responsible. You’re welcome, Chicago. 

My curiosity got the best of me. I doubled back and reached down to grab the paper airplane as if I was the one who had dropped it there. I opened it while walking back toward the intersection. While doing so, I could feel the eyes of a stranger peering down on me from above, waiting for me to react.

Here is what was inside of the paper airplane:

And now we keep the paper airplane on our refrigerator at home as a reminder there is kindness in the world, and it asks nothing in return.