Ubisoft has shown off footage of the new co-op heist missions in Assassin's Creed Unity.
Each heist sees you infiltrating a guard-filled area to locate and loot a chest. The position of the chest (and of the enemies) will be different each time, allowing for added replayability.
The video below shows Unity creative director Alex Amancio making his way through a mission aided by a fellow Assassin, controlled by another player.
Amancio and his friend make quick work of the guards by combining skills such as Eagle Sense and lockpicking, and from simply having two people to do the stabbing instead of just the one.