Two guys meet each other at night and one of them shows the other a box where there are three guns. Then a police officer appears and asks:
What is in the box?
Can the guy whom was shown the box whisper to his pal
Don't show him what are in the box! ?
I read that if we knew or presupposed about something that was plural we could say sentences like that with plural forms or verbs. This way the police officer doesn't know anything about the singular/plural form of what is in the box. Therefore he uses "is". However, the boys knowing the amount of the guns is three use "are". Am I right?
P.S. If he can, will it be wrong if he still says:
Don't show him what is in the box! ?