The Longest Night.

The daughter of a wealthy family is kidnapped and imprisoned underground in a custom-built, ventilated coffin while her family and the police search for her. But the battery that powers the ventilation is running out of juice and the ransom drop has been botched. This movie was originally shown as an ABC Movie of the Week on September 12, 1972. The story is based on the 1968 kidnapping of Barbara Mackle by Gary Krist.