The final clue you'll find is a hole in a wall. Once you find it, walk up to it and press to study it. This will trigger a flashback and the mission: Data Hive.
Note: Some people see to be having problems with the Junior Detective, Gumshoe, and Super Sleuth achievements. See below for a list of solutions.
- You cannot replay a level while in the middle of a campaign.
- You cannot go from playing a campaign solo to co-op or co-op to solo.
- If you're playing co-op, the person that studies the first clue should study all of the clues.
List of clues in order of appearance:
Dare's Recon Helmet
Bent Sniper Rifle
Hole in a wall