knowing nothing about sth :
Workers were kept in the dark about the plans to sell the company.
She arrived at the meeting as much in the dark as everyone else.
IN THE DARK (ABOUT STH)
Meaning of IN THE DARK (ABOUT STH) in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005