i was on the beach when my mobile phone rang

Last summer, I was on the beach with my friends when my mobile phone rang. My sister needed my car and she said it was very important. When I got home, my sister was very anxious because (her dog was lost/she'd lost her dog/the dog was missing/lost).
While she went to the police station in my car, I waited/searched near my house but couldn't find it.
Three hours later, we went back home very sad when we heard a noise in the closet. We opened it and my dog was sleeping in (on? - "in" would imply between items of clothing or even that your dog was wearing your clothes!) my clothes!!!