This mission once again starts by requiring you to go out and patrol Gotham. This time, instead of simply beating up baddies and collecting the clues they drop, you’ll need to interrogate someone who knows about what happened to Langstrom.
Before you leave the Belfry, take a look at the map — it should have premeditated crimes thanks to the clues you discovered on last night’s mission. Look for crimes where The Mob or The Freaks are listed as the faction, as this mission requires you interrogate a criminal from each faction. Track whichever crime is closer, and then leave the Belfry.
If for some reason you don’t have any premeditated crimes on your map, you can still find the criminals you need by looking for an area that has both criminal activity and one or both of the factions you need to find. The presence of both Freaks and The Mob are indicated in the example below.
Once you reach a crime with one of these factions, use the AR Scanner and scan the criminals there. Hopefully, one of them will have a red exclamation mark above their level number — this indicates that they can be interrogated for information. You should have just done the practice interrogation in the Belfry, but in case you forgot: To interrogate a criminal, you’ll need to either sneak up behind them, or weaken them via damage, and then grab them with and press /.
Once you’ve interrogated a criminal from the Freaks and The Mob factions, you’ll be able to go and speak to Talia al Ghul. Simply follow the indicator on the HUD, and it will lead you to the rooftop she’s waiting on. Once you get there, a cutscene will play, concluding this mission — fast travel back to the Belfry to continue with the main story!