For example, my opponent has "Holding the Trident" as active plot and only "Valar Morghulis" left in his unused plot deck. I play "Lords of Narrow Sea" from hand in Marshalling phase and force this opponent to reveal new plot card. He reveals it and Valar Morghulis kill everyone. Then we have disagreement:

What happens to Valar Morghulis card?

1) Does it become active plot and "Holding the Trident" moves to used plot pile?

2) Does it become active plot and "Holding the Trident" moves to unused plot deck?

3) Does it go back into unused plot deck?

Bonus question is: Can the players have different number of cards in their unused plot decks simultaneously?

keeca said:

The key here is that he "revealed" the plot. No matter when you reveal a plot, it becomes your active plot until something (like the Plot phase) lets you reveal another one.

keeca said:

For those who interested in plot phase framework, there's more information: www.fantasyflightgames.com/edge_foros_discusion.asp

Thank you for your clear answers!