Mark Sivertsen

The team are dispatched to a destroyer to probe the bizarre death of a sailor, discovering he was deeply immersed in an addictive fantasy role-playing game and may have been bent on exacting revenge on his arch rival.

Mary looks after a 10-year-old boy, serving as a witness and tries to stop the state from returning him to his drug-trafficking father.

The BAU travels to Chicago to investigate a series of mass murders, after teenagers in a missing persons report become the main suspects.

Upset that his case has fallen apart as a result of the destruction of the mobile drug lab, Hank risks his career by attacking Jesse; worried that Jesse will talk, Walt offers him a chance to team up again in his new lab.

The detective suspects Captain Stottlemeyer's girlfriend Linda could be a murderer.

Football-gear managers Jonathan and Mark discover a star player's injury has resulted in drug dependency.