Conan gets to watch over a two year old kid which names itself Santa. Ishikawa Shigeko, Santa's Mother, has been pushed down the cross-walk stairs. She is uninjured but mentioned to Kogoro Mori that in the last days she got the feeling that she is being watched by someone. She asks Kogoro to find out who is watching her. But in the middle of the investigation Ishikawa is kidnapped.