Be left in the dark (about something) idiom
If somebody is left in the dark (about something), he or she is hidden from the knowledge of something or kept unaware about something.
It is better that Corrie be left in the dark about the death of her dog. Let's wait until she finishes the exam and we'll tell her.
Why was I left completely in the dark about this new boyfriend of yours? Now I know why. He does not seem like a nice person.
Laurie decided that her husband be left in the dark about her bruise since he was on a business trip.
Used to tell someone to keep secret what you're about to say
To be secretly working together
Kept in secret
Uninformed or ignorant of something.
The verb "be" should be conjugated according to its tense.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.