Ordeal by Terror

"The top drawer of the second cabinet felt empty as she began to pull it open, but she never saw its interior. The floor dropped from under her. As she fell, she clutched wildly at the handle of the cabinet's drawer, but her grip had been too loose. It slipped through her fingers, and for an instant she fell into nothingness. Then she landed on a steep incline of smooth metal. Her feet hit first and instantly shot out from under her, and she fell backward with a thud that stunned her. She caught a glimpse of a trap door closing over her head as she slid rapidly down the incline into darkness."
A-Z Publications has provided Adelle Gernyan with a great salary and office but the mundane work assigned her doesn't merit such treatment. Annoying colleagues, spying maintenance men and a mysterious boss add to the puzzle of her strange job. Adelle's boredom changes to terror when she is trapped under her office building with her fellow employees. Subjected to hunger, sleep deprivation, deadly traps and the horrors of armed attack, Adelle doesn't know that she has become part of a vicious experiment on the human mind labeled only as "The Telo-um Test"... a test with death as its final grade.
This is a griping suspense story from an acknowledged master of mystery and science fiction, Lloyd Biggle, Jr.