What happened at Clare's house tonight...

Clare and i were sitting in her room and we were babysitting Clare's brother, my brother, and their best friend. Clare went to check on them and after she went down stairs i decided to go downstairs too. I walked out of her room and I thought I saw someone in the bathroom and I walked down two stairs and I went back up to see what she was doing in their and no one was their. Then we were in her room later on and we were painting and we had the door shut. The boys were downstairs watching t.v and we heard the beads hanging in front of her door make a noise. I cleaned the paint brush and opened the door too see who did that. I expected Charlie, Clare's dog, to be sitting their. He wasn't. the gate keeping him downstairs was shut. I went downstairs and asked the boys if they had gone upstairs and they said no...