Set in the year 2406, Captain Junius Fahrenheit, Major Jean Brookes, Officer Ashton Brookes, Ensign Claine de Lune, along with thousands of other United Terran Vanguard Soldiers, are thrust into mankind's first interplanetary war.
Sierra Ops is a game of consequences; the game features mostly what awaits people when war suddenly happens after a hundred years of peace. You will play as Junius Fahrenheit, who is one of the few soldiers that were forced into the very first interplanetary war.
After the Ares Confederation took control of the Lagrange colonies and Earth's orbital space, you were assigned as Captain of "Sierra", a very powerful experimental battleship. A privilege though it may seem, you were not fully briefed as to why were you given such a very critical responsibility.
In addition, you were tasked to reclaim control of the colonies using Sierra. Depending on your choices and courses of action during missions, the characters around you will be affected greatly.
Will you be a role model soldier who will follow your Fleet Command to the letter, they who have given you such power and responsibility?
Will you back out from the war and try under your best efforts to stop bloodshed under your own volition?
All is fair in war. Whatever your decision is, you are the Captain of Sierra, and ultimately, the one in charge in undertaking Sierra Ops.