- "Luckily, there's always one guaranteed weak link in any security set up. The human heart."
- — Carl Johnson.
Key to Her Heart is a mission in Grand Theft Auto: San Andreas given to protagonist Carl Johnson by Wu Zi Mu as part of plans to pull off a heist off Caligula's Palace from The Four Dragons Casino, located along The Strip in Las Venturas, San Andreas.
Carl has just returned from the Las Venturas City Planning Department with the blueprints of Caligula's Palace, which he and Wu Zi Mu intend to burglarize. The next step in his plans involves providing his team access to Caligula's restricted areas by wooing and gaining the trust of one of the casino's croupiers, Millie Perkins. Carl takes Millie out on dates and slowly convinces her of his genuine affection. Eventually, she trusts him enough to let him use her key card for the heist, the plans for which Carl has intimated to her. He assures her that she will receive a generous cut of the purloined cash, and takes her security card back to The Four Dragons Casino in preparation for the next steps of the plan.
In order to complete the mission the player must:
- Get to Caligula's Palace casino
- The Croupier has a keycard and knows the code, follow her
- She's gone into the sex shop, follow her inside
- The Croupier is in here somewhere, find her
- Go and get a gimp suit
- Leave the shop and go after the Croupier
- The Croupier has left the shop. Follow her but remember not to get too close
- The gimp will be arriving shortly, wait around and make sure he dosen't make it to the Croupier's house
- Now that the gimp's out of the way go and ring the doorbell
- After this mission, on your first date with Millie, you can just kill her for faster access to the keycard.
- A Love Fist poster can be seen when Carl Johnson and Wu Zi Mu discuss their plans to rob Caligula's Palace.
- This is one of only a handful of missions in the game that can overlap with others. Since Carl has to go on several successful dates with Millie, who is only available at certain times, it's possible to not only save the game, but undertake other storyline missions, side-missions and odd jobs (as well as date other girlfriends) during the course of the mission (note: this applies only after Carl successfully follows Millie home, kills the gimp, and makes her a girlfriend).
- Once Carl receives the pass card from Millie, he's under no further obligation to date her, but can continue to do so up to 100% progress, though there is no 100% award given for Millie (unlike other girlfriends).
- If the player has enabled the 'Hot Coffee Mod' in the PC version, this mission becomes harder because Millie, unlike other girlfriends, has to be spanked, which is harder to do.
- Although it is Millie's Keycard, it isn't actually her on the keycard. It is actually owned by a man called "Officer P Rowe".