Following the events of the last season, Sherlock and Joan work at repairing their partnership and, in so doing, discover a side to it which neither of them had anticipated. Whilst trying to come to terms with the true nature of their relationship, they find themselves embroiled in a case involving a ruthless killer, whose sights become fixed on Joan Watson. (Dedicated to RP&AW)

When your life is hanging in the balance, you realise exactly what's important to you. When Erin and Jay are kidnapped, they can only begin to imagine why. So when Jay's past comes back to haunt him will he ever be able to fix what's happened?