A wealthy businessman, Alexis Laurent is suspected of the murder of his ex-stepfather. Alexis Laurent is also a horse breeder and is already suspected of having killed his wife.
During the investigation, Melissa and Gaëlle discover that Cyril has infiltrated the equestrian center because Alexis is involved in trafficking and money laundering. Cyril proposes to Melissa that she help him in this infiltration.
A young student is found murdered near her campus. Melissa and Gaëlle discover that she was a camgirl. The investigation leads them to suspect one of their teachers who turns out to be Chloé's girlfriend.