Using cheats you can obtain this just by playing through the first level.
Main Menu > Extras > Cheats Codes > Enter "Quimbecile" (without quotes). This will give you 44/44 stars in MI6 Ops and unlock all difficulties with all objectives accomplished on Operative and Agent difficulties.
Choose Dam from the mission select menu, choose Agent difficulty and run through the level making sure you complete all of the objectives. The achievement will unlock when you jump off the dam.
The secondary objective on Agent difficulty is to download the helicopters flight plan. The wi-fi node you need to hack for this objective is found in the room at the top of the guard tower with the sniper towards the end of the level (secondary objectives are marked as complete up to Operative difficulty when using the aforementioned cheat).
If you don't already have it you will also unlock the following achievement at the same time.