09: Hope in Hadleys

1. Make your way to the laboratory and check the table beside the microscope to find the dog tag. This is near the sealed door that you have to cut open to rescue a marine.
Laboratory Dog Tag

2. Once you reached the vehicle bay, you'll be asked to set up a defensive perimeter. Head to the room in the corner where the ammo cache is located. There's a ramp leading to the maintenance trench. Follow it and you'll find the dog tag on the floor.
Vehicle Bay Dog Tag

3. After defeating the crusher, head to the next door and wait for Cruz to open it. Get inside and follow the path until you reach a workbench. You'll find another dog tag there.
Workbench Dog Tag

4. After reaching the dropship, check the crate in front of it, beside a payloader to find the mission's last dog tag.
Dropship Dog Tag