The following paragraph is from an American story. We learn that bad guy John, who is a CEO of a technology firm, and his wife Jill have an accident. There is no further context, i.e. the incident is only mentioned once and the details are irrelevant for the story, it's only the outcome that matters (hand of fate).

While passing through a riot area, their car was caught and rolled. Its defenses weren't breached, but a tank full of a defense-security compound that John was testing developed leaks as the car was righted. Nearby a liter of the stuff rained onto John and Jill. The test worked all too well. It was hoped that the couple would recover some eyesight, but much of the other damage was beyond ...

My question is: Does that sound natural at all to AE ears? Is it perfectly clear and understandable to you what happens or does it strain your imagination as much as it strains mine?

What particularly disturbs me is the double "defense". I guess the car was ambushed and turned upside down, but wasn't broken ("it's defenses weren't breached", sounds a bit odd, though). When the car was righted (turned over in its proper position), some "tank" broke. Just a can placed somewhere in the car? A tank installed in the car? What is a "defense-security" compound supposed to mean? Its a chemical compound, obviously. It has nothing to do with the "defenses" of the car, has it? Something you might use to defend yourself, like some teargas? Just incidentally there because John had been testing it at his company?

I'm just trying to get the "feel" of it, I'm not looking for the translation itself, that's why I put it in LangLab. I don't get the picture. Is it just me?

How do you read that paragraph? Any help appreciated.