Christmas has come again and the gang are throwing a party. At a ice rink, Markus tells his dad the only thing he wants for Christmas is for his family to be all together. When his dad leaves, Tommy switches places with Markus while he goes to visit his mother. While Markus is gone, Tommy is kidnapped.

A young married couple are shot dead. The killers then move in on a Professor Dorner who is perfecting a new medicine. The killers take the man's family hostage. Meanwhile, Moser has discovered that the couple were coworkers to the Professor and they track them down. Rex is sent into the house first to reassure the family.