It's 2552. The theocratic military alliance known as the Covenant is showing no mercy as it continues to assault every human world it encounters, but in the way lies humanity’s greatest champion, the supersoldier Spartan John-117 - the Master Chief. Together with his AI companion Cortana and the last remaining Spartans, the galaxy-spanning fight rages on two fronts following the destruction of the human military stronghold Reach by Covenant forces and the mysterious artificial ringworld known as “Halo” at the hands of the Master Chief. 

The 26th century. Humanity has expanded beyond Earth’s system to hundreds of planets that colonists now call home. But the United Earth Government and the United Nations Space Command is struggling to control this vast empire. After exhausting all strategies to keep seething colonial insurrections from exploding into a full-blown interplanetary civil war, the UNSC has one last hope.    

The 26th century. Once considered clandestine, the Spartan-II program has now gone public. Tales of armored supersoldiers fending off thousands of Covenant attacks have become the stuff of legend. While the Master Chief defends a besieged Earth and the myriad factions of the Covenant continue their crusade to eliminate humanity, an ultra-secret cell of the Office of Naval Intelligence known as “Section Three” devises a plan to buy the UNSC vital time. It will need hundreds of willing soldiers, though - and one more Spartan - to get the job done. 

It's 2524. Harvest is a peaceful, prosperous farming colony on the very edge of human-controlled space. But humanity has unknowingly trespassed on holy ground - straying into the path of the aggressive, theocratic empire known as the Covenant. What begins as a chance encounter between an alien privateer and a human freighter soon catapults all of mankind into a struggle for its very existence. But humanity is also currently locked in a bitter civil war of its own: the Insurrection. 

It's 2535. It is the first, desperate days of the Human-Covenant War, and the United Nations Space Command has enacted “the Cole Protocol” to safeguard Earth and its inner colonies from discovery by its merciless alien foe. Many are called upon to rid the galaxy of lingering navigation data that could potentially reveal the location of Earth and ensure the destruction of humanity. 

It's 2553. The theocratic military alliance known as the Covenant has collapsed after a long, brutal war with humanity that saw billions slaughtered on Earth and its colonies. For the first time in 30 years, however, peace finally seems possible. But though the fighting has stopped, the war is far from over: It’s just gone underground. 

One hundred thousand years ago, the galaxy was populated by a great variety of beings. But one species - eons beyond all others in both technology and knowledge - achieved dominance. They ruled in peace but met opposition with quick and brutal effectiveness. They were the Forerunners - the keepers of the Mantle of Responsibility, the next stage of life in the Universe’s Living Time. And then they vanished. This is their story.

In the company of a young girl and an old man, Chakas begins an epic journey across a lost and damaged Halo ringworld in search of a way home, an explanation for the warrior spirits rising up within, and the reason for the Forerunner Librarian’s tampering with human destiny.  

It's 2553. Welcome to humanity’s new war: silent, high-stakes, and unseen. This is a life-or-death mission for the Office of Naval Intelligence’s black-ops team, Kilo-Five, which is tasked with preventing the ruthless Sangheili, once the military leaders of the alien alliance known as the Covenant, from regrouping and threatening humankind again. What began as a routine dirty-tricks operation - keeping the Sangheili occupied with their own insurrection - turns into a desperate bid to extract one member of Kilo-Five from the seething heart of a brutal civil war.  

One hundred thousand years ago, Chaos rules the final days of the Forerunner empire. The Flood - a horrifying, shape-changing, and unstoppable parasite - has arrived in force, aided by unexpected allies, and internal strife has desperately weakened Forerunner defenses.  

While Spartans get all the glory, no soldier - not even the legendary Master Chief - wins a war on his own. Gunnery Sergeant Edward Buck and his team of Orbital Drop Shock Troopers (ODSTs) played a major role in saving the Earth from all-out invasion at the end of the Covenant War - acts of bravery and ingenuity that did not go unnoticed by the United Nations Space Command.

It's 2553. With the 30-year-long Covenant War finally over, the Office of Naval Intelligence faces old grievances rising again to threaten Earth. Angry and bitter colonists - still wanting to settle scores from an insurrection put on hold for three decades - crave justice...as does a man whose life was torn apart by ONI when his young daughter was abducted for the SPARTAN-II program.  

October 2559. It has been a year since the renegade artificial intelligence Cortana issued a galaxy-wide ultimatum, subjecting many worlds to martial law under the indomitable grip of her Forerunner weapons. Outside her view, the members of Blue Team - John-117, the Master Chief; Fred-104; Kelly-087; and Linda-058 - are assigned from the UNSC Infinity to make a covert insertion onto the ravaged planet Reach. 

It is 2555, more than two years after the Master Chief went missing in action following a decisive conflict on Installation 00 - the massive, extragalactic Forerunner construct known as the Ark - as part of the final chapter in humanity's bloody 30-year struggle against the overwhelming forces of the Covenant.

It is 2553, and the three-decade long Covenant War that defined a generation has suddenly drawn to a close. Yet in the remotest parts of human space, tensions remain that threaten to overflow into another full-scale conflict. Beneath the surface of the planet Gao lies a vast cavern system renowned for its therapeutic effects and rumored miraculous cures. But now Gao natives are turning up brutally murdered down there - violent acts that happen to coincide with the recent arrival of a UNSC research battalion.