This first part is a rail shooter section. You still have some maneuverability as you can detach the turret gun and run around with it, and you can check your flank in all directions for incoming ships. Pressing in the Aim button switches you to first person instead of over-the-shoulder this time around.
It's pretty straightforward. Kill everyone until Titus is forced off the plane via cutscene magic, and you'll hit a checkpoint.
With Titus' Valkyrie down, he calls 2nd Lieutenant Mira for transport. Unfortunately she's already fighting, so you have to go rendezvous with her. Once again, you're alone against a massive horde of Orks. Thankfully you're fighting in another tight corridor, so use grenades and your melee attacks liberally. Continue slaughtering your way forward; aside from the occasional tough enemy like a Shoota Nob, it's not too hard.
Once you approach the objective marker, Mira calls you back and says that a Valkyrie is on its way. She also tells you that Inquisitor Drogan made it back to Kalkys safely. A checkpoint will trigger as the next area loads.
Once the Valkyrie unceremoniously drops you off, you have a choice of some different melee weapons. Pick your favourite, grab some ammo and meet up with Drogan and your squad. After a short conversation, press forward. You should receive a new objective: Reach the Research Facility.
After a few seconds of running you'll be ambushed by some more Orks. Take out the Shoota Boy snipers and then focus on the ground forces. When you're about to apporach a bridge, head right to find some extra enemies and free grenades.
Keep pressing forward. The next Ork fight triggers when you're some distance away, so snipe as many as you can if you have ammo. When you approach closer, about five or six Slugga Nobz will attack, but thankfully you have your squad with you this time, so the fight should be a bit easier than in Chapter 8. Proceed forward to the objective marker.
A short conversation between Inquisitor Drogan and Titus should trigger when you hit this checkpoint. There's a Servo Skull (Medicae Station Ventris 5/5) right in front of you in the wreckage of a crashed ship. Pick it up and soldier on. There's some more ammo and yet more options to swap out your weaponry. It's really up to you what you want, as pretty much every weapon can get the job done in some capacity.
When you reach a bridge another battle commences. Once again, snipe as many as you can FIRST, and then go in for the melee and machine gun finisher. When you've crossed the bridge, head left for some grenades. Continue along that path and when the next fight starts, you'll find yourself in an excellent sniping position. You know what to do!
You'll cross yet another bridge. This time get rid of the Rokkit Boy way in the back, because he can be really annoying. Eventually a Slugga Nob Pro will join the fray. Shoot him and retreat, then shoot him again. You have lots of open space, so use it to your advantage, and don't let the Slugga Nob Pro get anywhere near you.
Cross the bridge and take the right fork for another fight. Run forward again, and you'll trigger another conversation with Drogan asking you to help him activate the Psychic Scourge. Pick up some ammo and run forward.
Approach the large door and prepare for a protection mission. For some reason this door has a complex locking mechanism that only Drogan can unlock when he's being ambushed by Orks. Or something like that. Make sure to grab the Thunder Hammer before you activate the first wave of Orks, because you'll need it.
The first wave is pretty straightforward. The second wave throws in some 'Ard Boyz for a little variety. The third waves has you facing multiple Slugga Boy Proz at once. The trigger for the end of the fight is only set when all the Slugga Boy Proz are dead, so focus on them. If an 'Ard Boy or two is left over, don't worry about it.
Proceed through the door to hit another checkpoint.
Move forward and pick up some ammo, triggering another conversation. Drogan will open the next gate for you.
Continue down the ramp and forward, triggering another ground fight with Slugga Boyz and some Bomb Squigz. Keep moving forward until you see some Rokkit Boyz firing down at you, and take them out. Continue on.
Head up the ramp of rubble onto a metal walkway. Kill some Gretchinz, keep moving up and into some pipes, of which Drogan will take note. Once you drop down, the chapter will end.