What: Spectators will have 150 minutes to unravel a mystery based on a 19th-century novel by French author Émile Zola, itself inspired by the department store.

Why is it important: Shoppers will have the opportunity to find out on Friday and Saturday nights starting Sept. 2, as the department store plans to offer a cycle of immersive theatrical productions in honor of its 170th anniversary.

Within 45 minutes of the store’s 7:45 p.m. closing time, 250 spectators will be welcomed into the store for a celebratory cocktail that will soon take an unexpected turn that will take them back to 1862 and the fictional department store.

The musical score will be performed live, as 40 actors live out 12 tableaux throughout the 150-minute playtime. Guiding the audience through the story — and the store — will be French journalist and radio host Fabrice Drouelle.

Le Bon Marché celebrates 170 years with immersive play