As soon as you gain control of Blazkowicz, you’ll be face to face with a Nazi officer who for some reason was in the trunk of your car. He's restrained, so explore the area before picking up the safety goggles from the desk drawer, then the plastic apron from the cabinet next to the desk. As soon as you grab the chainsaw from the desk, the officer will attack you. Melee him several times to knock him back into the chair before getting on with the interrogation.
After another cut scene, follow the old man's instructions and get ready to clear out the Nazis before the car can proceed forward. Jump down into the pipe to the left, prompting two Signal Detected notices to appear at the top right. Crouch and move in the only direction you can, taking out the guard standing at the top of the stairs with your Knife. Continue to move counter clockwise around the building until you see the patrolling Commander. Sneak up the stairs and use your Knife to take him out.
The second Commander is in the building further down the line, connected to the first by a catwalk. Go that way, doing your best to stay quiet. If you're caught, you'll have to deal with a Kampfhund and two or three drones. The good news is, once your cover is blown you can just shoot everyone which moves things along quite nicely. When the two Commanders and their goons are down, head back towards the car and hop on.
It's a fairly short trip until you have to jump off and start fighting again. Go through the door to the left and kill all the guards inside. No need to try and sneak just yet, they all know you're there. Clear them out and loot the room, destroying all the crates to get the goodies inside. When you're done, head up the stairs until you're on top of the gate (you'll see the car below you) and head across to the opposite side.
Fight your way toward the ground level, then open the hatch in the floor to drop below. Immediately go to your left, crouching to sneak up behind the two guards before taking them down with your Knife. Be sure to check the area for loot before moving on.
Once you start heading down the next set of stairs, you'll get a Signal Detected for the next Commander. As soon as you get to the bottom of the stairs, go underneath them and then counter clockwise around the room. This will bring you directly behind the Commander. Knife the Commander to prevent him from sounding an alarm and causing reinforcements to arrive. Once he's down, deal with the remaining bad guys however you want; there's no chance of them sounding the alarm.
Take the elevator lift to the next floor, then pull the lever to raise the checkpoint platform. Now head to your left and through the open door and up the stairs. Take out the guards ahead and pull the lever next to the door to exit the checkpoint.
This time, Anya's grandfather decides to drive off without you. Chase after the car until he instructs you to "shoot the Nazis." Do as the man says.
Immediately, you'll have another Signal Detected on your screen. Unfortunately for us, we got caught in the early stages of this section, causing the Commander to sound the alarm. This not only brought more bad guys to the fight, it also alerted several attack drones and a Kampfhund. The only plus side to all of this was that the Commander exited his office to confront B.J., allowing us to gun him down in the open.
Tip: If you were able to maintain stealth, work your way around the area in a clockwise direction. When you get to the back of a building with a ladder, climb it and drop through the hatch. You can use a Knife to take out the Commander from here.
When everyone is dead, head back to the car to trigger two giant robots to attack you. They are easy to take down. After rolling out of the way from under one's foot, quickly jump into the truck that he came out of and hit the button. Just like that, one's down and there's only one remaining. Now head to one of the turrets on the side of the road and open up on the second one. With both robots down, get back into the car to trigger another cut scene.
When you regain control, head over to the table and set the coffee down. You have to sit through some conversation with Obersturmbannfuhrer Engel, but you can answer her questions however you please, as the story will play out the same either way. Once your conversation is over, pick up the coffee and take it to Anya at the other end of the train, ending the chapter.