Missing

I think that we have some magical creature living in the walls of our house that likes to steal and hide Isaac's bottles. I know that I am trying to wean Isaac off the bottle, but doing it cold turkey isn't what I had in mind. It all started when we came hoe from California last Tuesday night. I swore I had 2 8 oz bottles, one that I brought to Ca and one that I left here. When I went to go use it, the only one in the house was the one that I had taken on our trip. Well, last night I go to use one of our 4 6 oz bottles and there was only 1! I couldn't believe it because the previous night I washed all 4 of them! Jim and I have looked all over the house and car with no avail. The only other thing that I could think of was that Isaac might have thrown them away but one would think that I would have noticed 4 bottles in my garbage can! So that leaves only 1 solution: a magical creature is living in our walls stealing Isaac's bottles. It only makes sense. So, what should I do to rid this pest from my house and recover my bottles?