Here is the full list of all 12 Monaco: What's Yours is Mine achievements worth 400 gamerscore.
Finish The Prison Break with a score under 1:10
Kill everyone in a mission
Complete Banque Albert without being seen
Finish any mission in single player with only wrenches
Use C4 to gib three attacking guards simultaneously without dying in single player
Play an entire song on the piano with 3 players
Revive an online teammate
Complete Campaign Act I Single Player
Win an online PvP match
Complete Campaign Act II
Complete each mission once without dying
Achieve all four trophies on every solo and co-op mission