Nikki travels to Mexico to attend the funeral of Luisa, a former intern at the Lyell Centre who was murdered in a carjacking in her native country. She soon stumbles across the post-mortem report and realises that the body is not that of her ex-colleagues. Assisted by Dr Eva Vasquez and fired up with the idea that Luisa might still be alive, Nikki and Jack trace her last-known movements and are led to a farm where a cartel massacre was carried out.