Oh no! Hope you get your kitty back.
I'm with the others you will have to watch and know exactly where kitty is and distract, move the cat when you leave.
My Nicky had no fear here...he liked to check out anything. During his life he got into the garage 2x. We quickly picked him up as he "hesitated" (indoor only cat who was still a little unsure thankfully). Otherwise we ALWAYS had to know where he was. I have to do the same thing with Heaven as she's impulsive. I always want to make sure I know where she is, especially if the door is open for a while if DH is loading/unloading something.
It's a good idea too, as you may find as your DC gets older that they "lock" them in a room by mistake. My DD did that one time when we were leaving...she closed Heaven in our bedroom and we were gone for 5 1/2 hours. We got back and she had urinated on a t-shirt that DH had thrown on the floor as she had no access to a litter pan (thankfully on the shirt and nothing else