The Cardboard Box (S07E06)

Susan Cushing approaches Holmes seeking help in locating her missing sister, Mary, but initially, he is not particularly invested in her plight. However, during the Christmas season, Susan receives a troubling package in a cardboard box, prompting Holmes to take a serious interest. This mysterious gift sets him on the path of a perilous criminal, intensifying the urgency of the investigation and leading to unexpected revelations.