Arriving in a paradise that caters to retirees looking for gentle waves and lemon groves, Chloë Cassens gripped her scorpion necklace and tensed her shoulders.

She was summoning the strength of her grandfather, a Holocaust survivor whose business empire was built on a talent for confrontation. The scorpion had become her avatar in a crusade against what she insisted was a case of corruption on the French Riviera — one that involved a freakish storm, a crumbling museum and an enfant terrible of modern art.

“Some family members think I’m insane for coming back here,” Cassens said, walking through the sunny streets of Menton, France, in full black attire. It was her latest visit on a yearslong quest to prove that the city had mishandled her grandfather’s legacy — a quest that also pushed her to embrace a more aggressive side of her personality.

“Nut up,” she said she’d been telling herself. “You are going to have to get over this anxious feeling of being perceived.”

Menton, a coastal city near the border with Italy, was where her grandfather Severin Wunderman had donated his collection of some 1,800 artworks, half of them by the French artist Jean Cocteau. In exchange, Menton built a jewel box museum, designed by the architect Rudy Ricciotti, to display them. But that jewel box became a ruin in 2018, less than a decade after the museum opened and her grandfather died.

Cassens said the architect had ignored local engineers and placed the museum on the shoreline with an open staircase leading to its basement archives. A storm destroyed the building after seawater overwhelmed its glass walls. Emergency crews waded through floodwater to retrieve hundreds of damaged paintings, illustrations and prints. The possibility of losing this vital archive of a beloved French artist was an unthinkable disaster.