A stunt assassination on this target is a little tricky. The mission ends immediately in failure if the target detects you, and plummeting from the sky and landing right next to him is just the type of activity that might get you Exposed. You need to attack the instant you hit the ground in order to complete the mission successfully.
The goal in this clip is to shoot the target from as far away as possible. I manage to shoot and kill him from 201 meters away.
The target is holding an ally spy captive - sort of. In terms of game mechanics, the so-called "spy" is just another civilian, except that she is programmed to walk around in a small courtyard. The target is simply programmed to follow her.
Like a regular civilian, the "spy" will run away if she sees anybody die. I throw an archer from high above into the courtyard, which causes the spy to run away. The target follows her and shoves her regularly.
The spy will probably run around the block for a bit, and then start to run toward the city. Jump down to the lower roof level, so that you can be close enough to lock onto the target as he passes by. Start aiming the gun before you lose your lock. Once the target is more than 30 meters away, you lose your "lock," but the aim on the target will be preserved regardless of distance.
As the spy runs toward the city, the target follows. They won't actually be able to reach the city, as the game doesn't model the world that far away from Ezio. The particular location where I shoot in this video was chosen to maximize the distance at which the game models the world, and to permit a clear shot to the target.
Free the Prisoner
The goal here is to free the captive spy without killing the target. Again, we can take advantage of the "civilian" behavior of the spy. Throw a dead body into the courtyard so that she sees it when she walks around. This alters the path she takes so that she leaves the guarded courtyard.
The target follows the spy closely. You can get rid of him by gentle pushing him until he turns away from the spy. The spy is now free, and she will probably walk to the city. Unfortunately, the mission won't end here, as the target must be killed in order to complete the mission successfully. Instead of killing the target, I kill the spy at the end just for the sake of confirming her identity.
Mysterious Death and Fast Travel Glitch
You can't ordinarily travel between maps when replaying an assassination contract. However, the game gives you a brief opportunity to do so after the target dies.
If you poison the target quietly, you can wait for the target to die at a nearby fast travel station. Watch the mini-map and the screen flash to indicate when the target dies. Immediately after he dies, engage with the vendor and pick a new city.
Your assassination contract will now only end when you exit replay or quit from the Start menu.
I kill the spy at the end just for the sake of confirming her identity.
That's what I do when I want to confirm a woman's identity - give her a little stabbing.