So my gaming group will be playing No surrender within the next few months (we wont start until end of the month most likely), and I need a way to keep them invested in the game after no surrender without relying on another book campaign.
Now one member of the group (the psyker) is increasingly becoming more corrupted due to terrible rolls throughout the last campaign. My plan is to reveal at the end (or near the end) of this campaign that his psyker character was in fact the one who was behind the events of No Surrender (and Final Testimate to a lesser degree) and has been a powerful servant of Tzeentch (maybe even the changeling) the whole time. When this is revealed he will lead the party into a trap and disappear after revealing his deception (tzeentch worshippers love to boast).
This will be the cliffhanger at the end of No surrender and hopefully the next few parts of the campaign will involve the players being seconded to the Inquisition and tasked to hunt down this character who will be working to some unknowable plan to throw the sector into disarray so that Chaos forces can conquer it. (Note: by this point the character is an NPC and the player will roll a new character)
So my overall question is: Is it a good idea to have one of the squad members betray the group?