NEXUS-47 Achievement in Hitman III
Complete End Of An Era.
How to unlock NEXUS-47Story-related; cannot be missed.
There are two targets to kill by any means necessary. On your first playthrough, once they're both dead, you'll need to make you way to the bottom floor of the ICA facility and get into the data core room to hack it. This will cause a security alert that is unavoidable on your first playthrough. Now you need to carefully get past the guards and escape the facility, at which point you can leave the mission to complete it.