In order to locate the Mechanist, the Sole Survivor needs to triangulate the signal being sent to RoboBrains-a model of robot with a human brain as a central processing unit-the units controlling each individual cell of robots. Lamenting her inability to save her owners, Ada agrees to join the Sole Survivor in the hopes of getting revenge and thwarting the wider threat posed by the Mechanist, the person assembling robots which have been attacking settlers and caravans across the Commonwealth. After repelling the attack, the Sole Survivor meets Ada, a customized robot who had been travelling with the caravan. The Sole Survivor intercepts a distress call from a trading caravan outside Cambridge, but arrives too late to save them from a horde of robots.

It consists of a series of quests that unlock the ability to build and customize robots at the player's settlements.

It is the first expansion pack and was released on March 22, 2016.