New Tricks (2004)

Jack announces that he he has decided to leave the team, but before Sandra, Brian and Gerry can question his reasons, Whitehall figure Stephen Fisher shows up with one of his secret cases featuring the unsolved murder of a woman dating back around a hundred years. With only 24 hours to solve it, the team attempt to find time to get to the bottom of Jack's surprising decision and attempt to persuade him not to leave.