Screen space to world space for non-player camera

I thought this would’ve been relatively easy, but I am severely stuck.

Basically I have this orthographic camera observing objects in the world, and want to do some line traces from it to the objects.

I don’t want to force the player to view this camera, i.e. the player controller will not have access to this observer camera. I had assumed there was something like CameraComponent->ScreenToWorld(X,Y) in UE, but I guess not. If anyone knows how I can achieve what I want I’d be very grateful

Thanks
K