This is The Guardian.

Hey, it's Babberton de Alessi here.

I've just got back from an epic road trip around the island of Ireland.

From exploring natural wonders and stunning cost of views to chilling in a seaweed bath.

It's a vibe.

Best of all, you don't have to pick between the Causeway coastal routes and the Wild Atlantic Way.

You can experience both iconic routes in one unforgettable trip.

Explore everything Ireland has to offer at the Guardian.com forward slash tourism island.

This message was paid for by Tourism Island.

The Guardian Archive Long Read.

My name is Scott Sayer.

I'm the author of What Lies Beneath,

The Secrets of France's top serial killer expert, published in 2021.

This story actually began with the editor of the long read, David Wolfe, who wrote to me asking if I might be interested in writing about it.

And to be candid, my initial response to myself was no, because I don't usually write true

crime.

I don't have an abiding, pre-existing interest in serial killing.

But in looking into it a little bit, I realized that actually this was a story both about

a particular person and a particular narrative, but also about the broader cultural

phenomenon of the serial killer.

And what I realized is that the serial killer culture that we're familiar with is actually

quite distinctive and is the product of the past 30 or 40 years and comes straight out of

...