Batman: Arkham Knight - Back on the Trail

Return to Mercy Bridge and get in the Batmobile, then go into the marker. Alfred will lower the bridge and you will be face-to-face with some drones, one of which will be a Diamondback. There will also be a new kind of drone, one which fired missiles at you, so when you see the warning that they are incoming, get ready to shoot them down with your Vulcan Gun.

You will also learn about a weak spot on the lesser drones, which is their little light right next to the cannon. If you hit this with your Vulcan Gun (zoom in with R3), then the tank will blow up in one hit. Once you've taken out the drones, go back to the trail and reactivate your forensics scanner to get back to tracking down the kidnapper. Of course, you won't go very far before running into more drones.

If you want, you can go around the island and destroy all of the drones, which will get you a nice XP bonus, although it will take you off of the trail that leads to Oracle. Should you do that and finish, get back on the trail and it will lead to the vehicle, which has crashed. Go into Detective Vision and follow the on-screen prompts to replay the crash scene. You find out that the body of the driver flew through the windshield, so follow its trajectory to where it landed.

Once you find the body, scan it to find traces of pepper spray, so return to the vehicle and examine the passenger seat. The door was knocked off the vehicle, so follow the trail and scan it to see it was opened before the crash, implying that Oracle got out just before the vehicle crashed. Find her location and follow it as she crawls, stopping when she's being shot at. Next, follow the bullet trail to find out the Arkham Knight got her, but there's one more thing bugging Batman about the crash. If you go back to where Oracle was crawling, you will notice that she tosses something underneath a nearby crate, so scan it to find an encryption device. To continue the main story, you will need to go to the top of Wayne Tower.