If this is the last Series how will it end?

[femaleBertieWooster]

It could be that an extremely important mission failed and each of the agents has a last closeup while they are realizing what is to be and possibly where they went wrong. Not a bomb taking out the world or all of Europe but something catastrophic to the planet or humans, something that would take decades to set right.

They would have to set each agent up with a choice during the episode so that they can realize later that it was the wrong choice.

The last shot could be on the person who actually made the first wrong choice that set up the events where the other wrong choices followed and we all know who that is.

Edit to add that, alternatively we could start with knowing that the mission failed and during the episode each agent, feeling guilty or inadequate, tries to fathom where he or she took the wrong path. The last shot of you-know-who would not just turn negative but go neg-pos-neg-pos several times, indicating thunder and lightening.