A visitor would never guess that in this part of small-town France, swimming pools are a common feature in the backyard.

If a house has a backyard, or a courtyard, the odds are good it will have a pool. Often one of those above-ground things, sometimes, but quite a few old-fashioned, dug-into-the-ground pools. For cooling off in the summer. For swimming a few laps.

But you rarely see the pools, from the street. Like other Latin societies, the French turn their back to the outside world, presenting often dreary walls, shutters and gates.

Inside, however, are all sorts of things, even in modest towns like this one. Gardens. Barbecues.

Swimming pools.

But you would never know about the water out back — unless, perhaps, you had spent your life in the town and understood the often complicated layouts of the houses here — and knew where all the pools are.

Which is how you apparently decided to sample a few of them on the edge of town — when no one was home.

Curious behavior, and it has produced our only little small-town mystery.

Who are the kids climbing walls and sampling swimming pools that don’t belong to them?

It sounds a bit like the premise of the John Cheever short story entitled The Swimmer, in which the protagonist decides to go home from a summer party via the neighborhood’s swimming pools.

Our own small part of this story was noticing, on a warm afternoon a few days ago, several teen boys frolicking in a pool at the house next door.

We could not see them, out our third-story window, unless they were at the south end of the pool. And I saw a guy, maybe 16, dark hair, swimming hard after a ball at the end of the pool. Perhaps it was a two-on-two water polo match? I shrugged and pulled my head back inside the window.

We had come to realize that this particular pool belongs to a house with almost zero exposure on the street. Not much more than a door.

We had heard rumblings about the owners turning up someday soon, so it seemed a little odd to not hear anyone going in and out … but to hear and see kids in the pool. It didn’t quite add up.

A few days later, after the caretaker had arrived and spoken with various neighbors, the story got stranger.

Apparently, the swimmers had begun by scaling the wall of our landlord’s place, on the ground level, and taking a few laps in her pool. This was last summer.

The landlord realized her pool had been “borrowed” when she found a music “blaster” left behind … along with one sock.

She supposed that the kids scaled the stone wall on the edge of her property, and found one stone apparently knocked loose in the climbing. No other damage was done.

Then last week, various neighbors (including us) heard kids in the next house over. Which has a bigger pool. No other sightings, no cars. Just the sound of kids in the pool.

And why should anyone be suspicious? Who “borrows” someone else’s pool?

A day or so later, when the caretaker come over to take a look, the pool was partly empty, and it seemed as if it had been used. She asked around, and several neighbors said, yes, they had heard kids in the pool and thought nothing of it.

They also broke into the garage, where the wine is stored, apparently, but we did not hear that it was touched — or the pool visit might have turned into a major party.

The other interesting part of it was how the kids got to the second pool — by entering via the wall they climbed over a year ago, then clearing the wall between properties by placing a ramp to the top and dropping in on the other side.

Who did this? Did they solve it as they went along? How did they know where the pools are?

It is a mystery worthy of Agatha Christie and Hercule Poirot, given that the protagonists are English and French (and yes, Poirot is Belgian, but he speaks French).

Does swimming-pool borrowing go on all the time in our town?  Is it just these two particular properties? Is it as bold as it seems? Or do the locals feel like, hey, this is our town, and we believe we can use any pool at a house not currently occupied.

Who knows?

That is what makes it fun.