A hook, to Monarch Star Divination, is a determining feature or a set of parameters that will set apart the target object from the world around it. Once she has the hook, she can use it to pull up information about the target into her eyes, the way a fisherman pulls up fish from a water body.
In this case, the hook is a powerful and fast entity, fast approaching their position from the north. There is only one object that meets this criterion in the area, so her eyes were able to lock on to it. All that was left was to pull up information about the target from the ocean of information around them.
But just as she was about to reel in the information she wanted, the fish buckled and resisted. This was because the owner of the information had held on to their information and refused to let it go.
