Sequence 3 - Roadside Assistance
Running up the road you will find two opponents and Vieri. You must defend your family and kill these thugs.  A moment later all soldiers will attack you, but fortunately your friends will help you. Kill your enemies. It is very easy to finish off those who are fighting with your companions - just come from behind and hit them. 
Sequence 3 - Casa Dolce Casa
Now talk with Mario Auditore.  Uncle will show you his fortress. Then he will give you another task - shopping. 
Return to town and go to blacksmith.  Buy leather pants and a dagger.  Armed with your new weapon go to a nearby doctor and get some drugs. Now, return to the fortress and to talk to your sister. Mario is waiting for you in his office.
Sequence 3 - Practice Makes Perfect
Speak with Mario.  You will find yourself at the training arena. You will learn how to avoid attacks, how to counterattack, offend the enemy and escape. At the end we will meet with the uncle.  After the battle go back to his office - you will find that everyone went to kill your family enemy.
Before you will follow Mario and his people go upstairs and speak with Claudia.  Run out of the town, get a horse and go to the location marked on the map. When you will reach the place, head to the church and talk to your uncle. 
Sequence 3 - What Goes Around
Run with Mario and his soldiers under the walls.  When your people will take care of the soldiers, jump over the wall (use crates). On the other side open the gate with the mechanism. 
Walk through the streets - Mario will give you some people from his small army. Command them to attack the guards and fight with them.  When the fight will be over go towards Santa Maria Assunta. You will meet a second group of soldiers - of course kill them all. They will be armed with maces - the best thing is to take their weapons away (SQUEARE when the enemy is attacking you, usable only when you are unarmed). 
At the fountain you will meet a wounded soldier, who will tell you to go to the square.  There will be a fight - run to your uncle who is in the crowd. 
Do not engage in combat - just find Vieri de Pazzi. You will see him from the roof of the building.  The battle will start but you have to focus on Vieri. 
Runs through the crowd of fighters and climb on the tower from the side, where there are no guards. At the top of it move close to the victim and kill him with your blades. 
After the battle you have to return to the villa..  Your friends will celebrate there but your uncle has some new plans. 
Sequence 3 - A Change of Plans
Follow Mario and read the letter.  Now go to his office, where he will tell you about some ancient texts. 
Climb on the villa roof and synchronize your view.  Now you have to find four Codex pages. All of them were marked on the map. 
The first one is next to the courtyard.  Another pieces can be found by opening the large map (SELECT). The second one can be found in the eastern part of the town. 
The third one is located in the western part of the city.  For the last one you have to use your horse to get to the eastern part.  Now return to your home for the next task.
This time, talk to Claudia. She will tell you about some financial problems.  More information about the development of the villa you will find in another part of this guide. 
Now speak with the architect to see what can be built at the moment.  The go to your uncle, who is waiting in the next room. 
We'll know about another secret of this stronghold - Sanctuary.  Now, you can go back to Florence - on horse or stagecoach located in front of the gate of the town. Go and visit your old friend, Leonardo.