To the DnD beyond Hive Mind...

I'm starting a Ravnica campaign soon and need some good ideas. Normally, I'm really good a storytelling and the lot, but I'm hitting a slump here...

I understand the lore mostly, but i'm having trouble coming up with something. I'm thinking of starting it as a mystery where the "people that sense crime" (can't remember the name of them) accuse part of the party for planning an assassination. They get throw in prison. Enter second part of the party to "rescue" them in service to one of the guilds. From there, they figure out what went wrong. A man hunt goes underway. The "people that sense crimes" don't want to admit they may have made a mistake. A first ever, and the campaign begins to unravel that bit while getting into the intrigue of Ravnica, pitting guilds against guilds...

I know it seems like a lot, but I'm stuck at certain points and just need some guiding ideas/advice on pushing this forward..

Please help,

Your friendly MurderHobo DM

It sounds like the plot of Minority Report. Honestly, that movie would make for a decent Ravnica game. 

It sounds somewhat like Minority Report: Ravnica. Watching Minority Report might give you some ideas. Either way, I think that starting with the reason why the mistake was made would be the way to go. Is it because someone paid off the guild to get the party members out of the picture? Or perhaps to put them in a position where they could be "rescued" and redirected to their purposes? Has someone corrupted their ability to predetermine crime in some other way? Or is someone impersonating that guild to discredit them?

This will help you determine who the BBEG is and likely what their motivation and big picture strategy. This should help unlock enough of the plot points to give your party something to work with.

House Dimir could've gotten leverage on the precognative mage that "made the mistake," and maybe it's a deliberate smear job. They manipulated the information so that when some big crime someone else was planning on doing goes down, the authorities are busy chasing the party who then have to clear their name. 

Maybe Dimir and the Orzhov could be working together if you want there to be spy stuff *and* mafia stuff? 

I ran a Ravnica game with a similar plot: The players were arrested for a crime they hadn't committed (killing an Azorius official). An Azorius higher-up  I only referred to as the Benefactor was a good friend/relative/girlfriend (hadn't decided yet) of the murder victim, and wanted the players to suffer for the crime, so she arranged to have them escape from prison via a convenient power outage. The major story beats:

• The party went to a Kraul village in the undercity to get information and smash faced. The information didn't amount to much other than learning that only someone high up on the Azorius ladder could orchestrate a power outage at the prison, but they did get pretty hammered.
• The letter they received from their mysterious benefactor in prison advised them to meet at a Rakdos circus, where the benefactor hoped they would get killed. It was a red herring, but it was a fun scene to role-play.
• After getting out of the circus, they were assaulted by street thugs hired by the benefactor to make sure they were properly dead. They never got to this point in the game, since we had to finish early (it was planned as a one shot), but I had planned that they would find a letter on one of the thugs signed by the benefactor (a bit of villain stupidity, maybe, but it was a one shot, I didn't have time to make a big mystery)
• I don't know what the players would have done, but I imagine they could use their contacts to orchestrate a time and place to assassinate the Benefactor, or simply "visit" them in their office

Thanks for all the good stuff, folks :)

I would pull/view cards from the ravnica box set, easily google-able, and try to get inspiration from the cards there, or the flavor text written on the cards. Can't get any more Ravnica than that.

Obviously, the maze race to control ravnica would be good, if not a much higher level story arc.

Maybe the precognitive mage sees that they will attack an Azorius official.  When they break out of prison, they'd probably try and figure out what the deal is, and in investigating they find that the officer in question is actually a Dimir agent that they have to fight, so that the mage was right all along.