From Amazon
After Blood Red Rivers and Flight of the Storks, Jean-Christophe Grangé breaks through the barriers of the traditional thriller. As a child Diane Thiberge was the victim of an assault. Now aged 30, an ethnologist specialising in the study of predatory animals, and a woman adept in the martial arts, she believes she has at last found a meaning and purpose to her life when she decides to adopt a five-year-old Thai boy, Liu-San, whom she christens Lucien. A nightmare ensues, however: on her return to France, Lucien has an accident and is declared to be brain-dead. A series of murders make Diane realise that her son is no ordinary child, but the prey of sinister and paranormal forces.

I read this a while ago but can’t now remember the details.