作為一部包含形上學轉折意味的間諜驚悚題材的電視影集，《相對宇宙》講述了主人公霍華德·斯爾克（Howard Silk）的故事。霍華德是官僚主義盛行的聯合國機構中的一名低級員工，他在某日發現他所供職的機構正在守衛一個秘密：平行宇宙穿越。通過霍華德和他在平行宇宙中的對手之間的故事，本劇展示了身份認同、理想主義、假定主義和失去愛等主題。

Saeko Shirasu is a 25-year-old war front-line photo-journalist who became a celebrity after taking a picture of civilians raising a makeshift UN flag in war-torn Uddiyana. The image then became an instant symbol for peace. However, just before the peace agreement is achieved, the flag was stolen by an armed extremist group in order to obstruct the truce. The UN peacekeepers decide to covertly send in a SDC (pronounced as "Seedac"—Special Development Command) unit to retrieve the flag. Because of her connection with the "Flag" photo, Saeko Shirasu was offered the job of following the SDC unit as a front line journalist. Among the SDC unit's equipment is the HAVWC (High Agility Versatile Weapon Carrier—pronounced "havoc") mecha armored vehicle.