Spoiler Alert: If you're my players, stop reading! There might be spoilers about Lost Knowledge and Trouble Brewing, also.

I have a campaign arc that I want to see if it could be further improved. I'd like ideas on how to twist it and make it fun and mysterious.

OK, here's the lowdown: the PCs started the game either as defecting ISB interrogators, prisoners or pirates. The group stole the prison freighter and crash landed on Formos, starting the Trouble Brewing adventure that's long since completed. One of the NPC prisoners who escaped before the crash was a jedi, and gave them some info about the location of the Athiss ruins (see Lost Knowledge).

Unbeknown to them, the PC's prison escape was orchestrated by an Inquisitor seeking to use them as deniable assets who could then seize the artifacts contained on Athiss without the higher ups in the Empire knowing. I'm thinking of a Sith Holocron for the artifact (more specifically Vodal Kresh's holocron), but with a narrow focus on alchemy and sithspawn (which I would have total control over, since it's all custom material I'd create anyway).

Basically the pirates who "freed" the PCs by attacking the freighter were hired by him and a bounty was placed on their head right after. The surviving crew of the prison freighter was summarily executed to leave no witness. The Imperial Databanks erroneously mentions that the entire crew is MIA, including the runaways.

Plus, in the background, the Inquisitor is indirectly filibustering the ISB / Internal Affairs to prevent further investigation on the missing crew. This helps explain how they got away with it, and alleviates the "Totalitarian surveillance" problem that could have made the game less enjoyable (http://tvtropes.org/pmwiki/pmwiki.php/Main/BigBrotherIsWatching is more Shadowrun than Star Wars, honestly). I only insist on the dangers of being spotted when it makes sense in the story, but not all the time, which would paralyze players.

I've pretty much based the entire arc around the PCs being somehow used by the Inquisitor. He's obviously a treacherous villain vis à vis the Empire, but it totally fits the arrogance of dark siders. And he is also devious, and while he can reliably find them using Force Seek (which is totally something he'd use), he also uses the information he redirects to himself to find out when they are going to act on the info they got.

To introduce further conflict inside the arc, I've introduced the players to a paradoxical character, an agent of Imperial Intelligence counter-investigating the case. I'm playing the IA vs. ISB rivalry, which leads the IA agent to avoid endangering the PCs since she wants to pin who's really behind their escape. Her colleagues probably think her worries are just crazy talk, but since it's what they always do anyway, she's not hampered in any way. She has met the PCs and warned them that something was out of place, but that for the moment they should continue to do whatever they intend to do. She has hired private agents to bribe one of the indebted PCs into giving regular reports of the party's situation.

Last game, the players finally landed on Athiss, and are on the verge of getting the Sith Holocron. My question is, how can I use the elements already in place in addition to perhaps new elements, to make the best of this conspiracy arc and heighten tension, curiosity, etc.?

I was thinking that the players could somehow "guess" they are being tracked by being attacked at weird places by disposable hired guns.

Since the captain of the initial pirate ship has managed to escape capture, despite the bounty on his head, I was thinking he could have been re-hired, in exchange for his bounty removed, by agents of the Inquisitor in question. The players, who often check bounties for some reason, would be tipped off by his bounty's disappearance and see him again at some point (which always makes for nice moments, recurring villains and all, plus sowing confusion).

Also, the use of Imperial Agents has to be as natural as possible, since there is already two "factions" involved: the IA agent who wants to set things right and find the traitor, and the Inquisitor antagonist who uses the PCs and masterminded their escape.

Of course, this campaign has lots more NPCs and subplots I'm not mentionning, and the arc I'm talking about is the "meta-arc". I was thinking it would be nice when, finally, the players face the Inquisitor, that it be epic. I don't want to "waste" him in a cookie-cutter scene.

Do you have ideas / suggestions? Red herrings to mislead the players?

Where are you in Lost Knowledge? Specifically, have they encountered:

-The lost Hunting Party

-The crazy old man

I've modified Lost Knowledge for the XP level of the players, making it substantially tougher, including a homebrewed Terentatek monster (by looking at the Beast of Kressh from SWTOR) and a lengthier Tomb complex (underground pyramid-styled). If I had entirely followed Lost Knowledge, they would have "defeated" the Dark side illusion and headed towards the Crystal Cave, but I've added a "special chamber", the Vodal Kressh repository, where the holocron is stored. The game will start with them facing the Kel Dor jedi who initially gave them the info, since she is slowly falling prey to dark thoughts after having been tortured, and now wants the holocron for herself, pretending (to herself) she wants to get rid of it. Since they are dark siders, them fighting a jedi sounded interesting, plus this also ties with the first session, which I find important (to tie sessions that are far apart together). Of course, things could go either way, but I predict my players will fight her, though if they decide otherwise, she would have been a nice mentor in other circumstances.

Edit: They have encountered the lost party... slaying them all in a rash and violent manner, which caused some intra-party conflict, and Conflict points. The hermit is still alive, and I roleplayed the hell out of him to "warn" them of the warping influence of the Tomb.

How many are actually force sensitive?

And are there any spies working for the Inquisitor part of your players' group?

Sounds like there should be so they can either alert you know who when they have the Holocron or calls them in to be ready when they know they're about to move on the Holocron's location.

Then there's the ISB Agent, is she being watched and whose backing her up?

As for the Pirate Captain maybe announce he was killed to keep them from being suspicious until he turns up to steal their prize and then let them think he's working for one of the Hutts or Black Sun rather than the Inquisitor since he should only turn up when you think the party is ready for the revelation after all for all I know its like Vader turned up in the first episode of Rebels and confronts Kanan... might have to prepare for the possibility they aren't ready to face the Inquisitor or maybe have him deal with the ISB Agent allowing the players to escape knowing they're really in trouble now!

I think you might have overplayed your hand with the ISB agent meeting and talking to the party. It might be time for her to show up dead, but obviously in such a way as to indicate she was trying to get in contact with the party. I like the idea of removing the bounty on the captain, but I'd leave that thread loose for the moment. Bring him back into the picture an ally to whichever faction has the least power at a crucial point a few sessions down the road -- likely at a meet to sell/trade the holocron.

It might be interesting to throw another faction at the party, too. The lost hunting party would have been interesting if they weren't immediately slaughtered. Perhaps they were sent by another group also looking for the holocron. Lastly, consider adding in a group that's interested in destroying the holocron for the greater good -- some Jedi remnants or somesuch.

In short, keep the party guessing about who's allied with whom and what their goals are. Make sure that everyone presented wants to help the party get the holocron -- just make sure to share the reasons as to why as transparent as possible. The party will come up with some very interesting ideas which you can appropriate to make things as amusing as possible. Also make sure none of the NPCs trust one another (except one who trusts everyone) to sow more confusion.

You know I read this and thought what if the Inquisitor had a rival, one who disappeared on Althiss which made their Inquisitor very curious.

However that Inquisitor didn't die he actually remained studying the shrine but I was wondering what if he was using this to test potential apprentices?

So he can access the Holocron but has ulterior motives and that ISB Agent is actually using the PCs when she stumbles onto him so she has a legitimate reason to call in the nemesis unaware who she should be scared of.