Here is the full list of all 27 Thieves Gambit: The Curse of the Black Cat achievements.
Started a romance with Bouchard.
Charmed the Duchess.
Discover Nick's true identity.
Charmed the Duke.
Refused to join Bouchard.
Went in over the garden wall.
Went in disguised as a maintenance team.
Charmed the heir.
Become the world's most famous jewel thief.
Double crossed Bouchard.
Teamed up with Bouchard.
Start a romance with Nick.
Dance with Nick.
Revealed Ludomir Ivankov.
Steal the Black Cat.
Escape the palace.
Went in through the front door.
Start a romance with Rania.
Investigate the palace.
Dance with Rania.
Recruited Nick.
Escape the city.
Recruit Le Roux.
Recruit Nora.
Recruit Rania.
Escape the Paris police.
Succumb to the Curse of the Black Cat.