It was a hot, sticky night in Phnom Penh in June when my producer Kyle Taylor and I went walking through the city’s red-light district.

A stone’s throw from the Mekong River, this is where grey-haired white men come to socialise with young Cambodian women – for a fee.

We’re here on the trail of a high-profile Australian barrister. As we chatted with revellers and working women, the secrets of Mark Dennis — or Dark Menace as he called himself — slowly came into focus.

We only intended to spend a week in Cambodia, but so many people had stories they'd been waiting to share, so we stayed to listen.

Day by day, we met people in their homes, on stools in busy markets, on the sides of horn-filled streets, and filled in the blanks of this mysterious story.

It’s an investigation months in the making, that shines a light on a story many would prefer to stay hidden. Join me, Charlotte Grieve, as we explore the late barrister's alleged heinous crimes, and ties to a much-loved children's charity, Sunrise Cambodia.

Lift the curtain with part two of Background Briefing’s new series, Dark Menace, streaming now on ABC listen.