DIsappearing hen at night

[crebellocfd]

I have 9 hens , mixed ages mixed breeds. At night our buff has been flying over the coop fencing and disappears , returning at sunrise squawking to get back into the coop. Obviously we have not been able to watch where she is going and we have searched all the trees and bushes around the coop. She is nearly egg laying age but if she was laying on a secret nest I would think she would be doing this during the day not at night ? anybody have any ideas ? I think its time to set up a camera

 

[Folly's place]

I would cover the run with netting at least. Birds flying out also means predators able to get in! Sometime she will probably get killed out there, too. Mary