Folle à tuer (Mad Enough to Kill) Evil Trap (1975)

Julie Ballenger has spent five years in a psychiatric clinic. Leaving the clinic apparently cured, she is hired by a wealthy industrialist, Mostri, to work as a governess to his young nephew, Thomas. The boy is heir to a huge fortune after the recent death of his wealthy parents who died in mysterious circumstances. During a visit to a park, Julie and Thomas are kidnapped at gun-point and driven away to deserted quarry. The two hostages manage to escape, but are closely pursued by an armed killer...