The story is set against the backdrop of the United Nations Space Command (UNSC) military academy, where a group of highborn cadets are training to join the ongoing war with the outer colonial planets. For generations, humans traveled the stars and worked together to settle worlds under the banner of the UNSC. But that peace has been shattered by insurrectionists, causing a galaxy-spanning civil war to break out. Among these cadets, Thomas Lasky struggles with doubts about the war and the burden of expectations he may not be able to carry. As he comes to terms with his potential as a military leader, the academy comes under attack from a terrifying and brutal alien assault. Lasky must fight to protect the academy and its students alongside a mysterious ally – an armoured super-soldier known only as the Master Chief – as their fates become entwined for decades to come.