Assassin's Creed: Freedom Cry

Story related cannot be missed.

This will be the first trophy you unlock and is obtained in Memory 2 - A Common Enemy. At the start of the missions/memory, you will wash ashore after your ship was destroyed by the storm at the end of Memory 1 - The calm before the storm. After you awaken and the cinematic has finished, chase the man who is in pursuit of the female slave; then the trophy will unlock once you have killed him and the subsequent cinematic has finished.