From Diablo Wiki
Home Invasion is an event taking place in the Ransacked Dwelling in the Westmarch Commons in Act V. This is one of the events to be completed to obtain the Sightseeing and The Tourists Achievements. The goal of this event is to rescue a family from a gang of bandits. When you enter the house, Brigand Looters attack you. So what do you do? You kill them! (Can't help yourself, can you?). In search for survivors, you encounter a girl, Cailyn. But she is surrounded by bandits who you need to kill too. You now go on looking for Cailyn's parents. When you find them, they are, again, surrounded by villains but this time accompanied by a boss: Bertram Thistwhistle. You need to slay them of course but alas the father does not make it. Now the last thing you need to do is to rescue Mia, Cailyn's sister. She is in a sort of panic room located at the end of a secret alley you can access from a hidden passage behind a bookcase. Unfortunately for them, Virgil Cutthroat and his men are already there trying to access the panic room. After a few more kills, you rescue Mia and the women of the family can finally be together again.