Inside the Paris attackers' inner circle

The men dance to their favorite rapper, Lacrim, in a nightclub on Brussels' chic Avenue Louise.

Brahim Abdeslam, clearly visible, with a cigarette in his hand, flirts with a blond girl, while his younger brother Salah, dressed in an orange sweatshirt, whoops along with the group in the background.

This is a side of the Paris attackers that has never been seen before.

The date is February 8, 2015.

Just over eight months later, Brahim would blow himself up at a cafe in Paris's 11th arrondissement. His suicide was part of a deadly ISIS mission that would kill 130 people and injure hundreds more. Salah would become the only known member of that cell to survive and go on the run.

Fast forward another year to March 2016 and Salah is captured in the Belgian capital, which itself is rocked by its own twin attacks, bringing the effects of the Abdeslams' terror network right to the heart of their home city -- a city where those who knew the brothers reflect on how so many of their inner circle could have been radicalized so quickly.

Inside the story of the Paris attack

Two friends, who filmed the video as they partied with Salah and Brahim that February night, agreed to share their stories with CNN, under the condition we hide their identities and speak far away from their neighborhood of Molenbeek.

So we meet in a park downtown, moments from the scene of the atrocity at Maelbeek metro station.