OK so this is a heavier mystery than I usually bring you, but it's the kind that gets its hooks in and won't let go and I can't stop thinking about it.

A couple was found dead in a hot tub at a property in Spain, and the people who found them were kids. That part is almost too sad to hold in your head. And now experts are pushing back on the official explanation for their deaths, and the whole case has gone from tragic to genuinely strange.

The details of what investigators originally concluded aren't fully laid out, but outside experts who've looked at the case aren't convinced the official story adds up, and they're saying so publicly. When people who do this for a living start raising their hands and going "wait a minute," I've learned to pay attention. My favorite genre of expert has always been the politely unconvinced kind.

You can read the full reporting over at the Mirror, which has the details of what the experts are disputing.

Cases like this are hard because a hot tub death looks, on the surface, like it should be simple to explain. Small space, two people. But the more questions you ask, the more the simple version wobbles. How did both of them end up unconscious at the same time? Why didn't at least one of them get out? Those are exactly the kinds of questions skeptics ask in cases like this, and apparently the official answers aren't landing.

I cover a lot of mysteries on this site and the pattern is almost always the same. Something happens that looks obvious, everyone nods, and then one person, usually a scientist or a stubborn relative or a retired investigator, keeps pulling the thread. And months or years later the whole original story unravels. Sometimes it unravels into a boring answer anyway. Sometimes it unravels into the Franklin expedition, where DNA just quietly gave a sailor his name back 166 years later.

For the family, and especially for the kids who found them, I hope the truth comes fast and comes clear. Somebody's parents are gone and the explanation itself is now a question mark, and that's a brutal thing to carry. That part never fits in a headline.

I'll keep an eye on this one the way I keep an eye on the Taos Hum and the sonar structure, filed under "the world hasn't finished explaining itself yet." Because sometimes it eventually does explain itself, and when it does I'll be right here, delightedly baffled along with everyone else.