An important Scientist Dr Bruckner has defected from East Germany, set to work with Department Seven, but he is intercepted by the head of a secret organisation, Mrs Arden.
This is an excellent final episode, it's creepy, deep and engrossing, the characters are each at their best. We get answers to most of the questions that have been asked throughout the series. It delivers some real shocks, not all of the main players get out alive, this was certainly dramatic.
Edith MacArthur is absolutely brilliant as Mrs Arden, she's chilling, a terrific adversary for Tom and Department Seven.
I wonder if they knew this was the end, or if they were hoping for a second series, on this evidence it could well have continued for a few more series. Such a shame many of the threads remained dangling. 9/10