Sherlock: the mechanical century

After discovering an inexhaustible new source of ether-based energy, Mycroft, Sherlock Holmes’ brother, has disappeared. His discovery is no longer safe. Energy magnates will do anything to make the object that threatens their power disappear.
Sherlock needs you! While he is investigating his brother’s future, he asks you to go to Mycroft’s offices to find and recover this energy source and announce his recipe to the world. All this, leaving no trace of your passage. How will you proceed?