Went by working title "Meurtre à Saint-Malo: 10 Ans Après" ("Murder in Saint-Malo: 10 Years Later").
Swann Arlaud was approached to reprise his role from Murder in Saint Malo (2013) but was unavailable. Aurélien Wiik meanwhile had signed on to return as Ronan but broke his arm four days before filming and was thus replaced by Baptiste Caillaud.
Was initially supposed to start filming in mid-September 2022, but the script and casting weren't finalized by that point, so production only got underway a couple of months later.