The Vanishing (1988, Neth/Fr.) (aka Spoorloos)

In director George Sluizer's original and haunting Dutch thriller:

• college chemistry teacher and genial family man Raymond Lemorne's (Bernard-Pierre Donnadieu) creepy preparations to abduct a woman (i.e., a sling with a fake, removable cast, chloroform, a log of his pulse rate after approaching various prospective female victims, a formula connecting "dosage" with "minutes unconscious" and "miles", etc.)
• the scene of the mysterious disappearance of Saskia Wagter (Johanna ter Steege) at a French gas station (by chloroforming her into unconsciousness, shown in flashback) while on a trip through France with lover Rex Hofman (Gene Bervoets)
• the chilling shock-ending finale three years later in which her abductor Lemorne planned a similar hideous fate for Rex by drugging him and burying him alive in a coffin under the earth