If it’s an existing film, stick it in Examples.

I would lead with the protagonists and I reckon it can be shortened slightly but it is a difficult film to logline and a good example of how an established writer/director can pretty much do whatever they want!

A group of teenage boys’ obsession becomes unraveling the mystery of five reclusive teenage sisters who, one by one, take their own life. (23 words)

OR

A group of teenage boys’ obsession becomes unraveling the mystery of five teenage sisters’ reclusive upbringing by their overprotective parents who, one by one, take their own life. (28 words)

They all commit suicide in the end if I remember correctly, so whilst the first is obviously the inciting incident I think it’s important to build on that because THAT’S the mystery. One girl killing herself is a tragedy, two suspicious, but 3+ and then you have a story! I’ve added that both groups were teenagers as I think it’s important to understand the group dynamics at work on both sides. They are all on the cusp of adulthood, so it’s kinda of a coming of age story too.

Whilst commas are frequently frowned upon in a logline, I’ve added them here as they actually tell the story in my opinion. Without them, and the “one by one”, you could assume they did it at the same time. I feel like with it in, you’ve got a 90min+ runtime. Combine that with the title “The Virgin Suicides” and everything clicks into place. I think a reader should see the title, read the logline, then look at the title again but this time with a deeper understanding.

I’ve added the parents in the second one as they are the antagonists. It’s arguably hinted at in version 1, but explicitly stating it in v2 removes any doubt.

The only other thing I’m uncertain about, is whether to include the time period. Whilst it’s not essential to the story per se, it adds a layer of understanding to the social dynamics at play.

This is a really interesting film to logline! I think your version is pretty good too tbh.