Ac 2 v 41 - Beginnings of a Conspiracy
0Unlocked After: Sequence 6 - Memory 2: Romagna Holiday
You're after three guards. You must kill all three without being detected. The only problem is that each of the three targets is with company. So, you'll want to purchase some Poison for this. You can deliver poison to a target to effectively kill him without being detected. The guard closest to the Abbazia Di San Mercuriale is patrolling with three other guards -- just use Eagle Vision to identify him. Throw some coins down to get the other guards out of the way, and then hit the target with poison and make for the next one.
The other two targets are also with guards, but you should be able to poison them right in front of the others without being implicated. Poison both guards and wait for them to keel over to complete the memory. - https://www.supercheats.com/guides/assassins-creed-ii/