', serves as the direct sequel to "Peace Walker" and is composed of two chapters. The prologue, ', is set a few weeks after the final mission in "Peace Walker", as Big Boss is tasked with rescuing two VIPs from a U.S. military black site on the coast of Cuba. Big Boss' mission coincides with a visit to Mother Base by the IAEA, which turns out to be a cover for an attack on Mother Base orchestrated by the mysterious organization XOF. In the chaos, Big Boss' helicopter collides with another, and he is sent to the hospital for nine years, which leads to the events of the main chapter, "The Phantom Pain". The basis of the main story revolves around Big Boss forming a new private military company, the Diamond Dogs to retaliate for the destruction of MSF and the loss of his comrades. However, this "Big Boss" is revealed to be a part of the medical staff who survived the helicopter crash, who was brainwashed to believe himself to be Big Boss, while the real Big Boss went into hiding to create Outer Heaven, a place where soldiers can live without having to abide by any particular ideology.