异次元人亚波妄想侵占地球，炮制了一系列宇宙怪兽和地球生物合成的超兽。被称为第1号的超兽贝劳克恩在日本福山市登场。前去迎战的地球防卫军全军覆没。这时，在惨遭破坏的大街上，有二位把自己生命置之度外的青年，他们是面包房的驾驶员北斗星司和护士小姐南夕子。二人竭尽全力救援遇难的人们，但终于精疲力尽倒在瓦砾中……救了他俩的是艾斯·奥特曼。艾斯把自己的生命溶入了二人的体中。 北斗和南夕子为了继续与亚波人战斗，参加了地球防卫军TAC，经过顽强地训练，终于战胜了贝劳克恩。 艾斯的战斗能力日趋强大，在自身掌握的特殊的光线技能和奥特兄弟的协助下，战胜了超兽和超人艾斯杀手，并会同奥特兄弟在异次元空间同亚波人展开了殊死的决斗。月球人的南夕子返回月球后，艾斯便附在北斗一人身上了。重任在肩，艾斯持之以恒地与超兽、亚波人搏斗。在击败了亚波人最得意的合成超兽后返回了光之国——奥特之星。

21世纪，地球回复昔日的和平，但此时宇宙坠下一颗陨石，陨石有一个人工的时空囊。地球和平联盟TPC的GUTS小队通过时空囊了解到地球将有大灾难发生。而此时，时空囊预言的两大怪兽·“哥路渣”和“米路巴”先后出现，GUTS小队便根据预言寻找收藏在金字塔的三大巨人的身体。 几经寻找后GUTS队员们终于找到金字塔，但两大怪兽也到来了。虽GUTS拼死守护，但三个巨像已被破坏剩一个，队员·大伍的战机也被击中，且逃生装置失灵。在危急关头，大伍突然化成光，和最后一个的石像结合。光之巨人“迪加”因此而复活，并与两大怪兽展开了战斗……

Ultraman Tiga: The Final Oddysey was sort of an epilogue of the Ultraman Tiga series. Just when we thought that the world is safe, it's under attack again! A TPC excursion (including GUTS' Captain Megumi Iruma) headed to an old ruins and unintentionally woke up three evil ancient giants whom Daigo, later on, has visions of. What's so haunting about his visions is that they're not only three but four evil giants, including Ultraman Tiga in a very dark physique and a very evil aura. After a series of visions, Daigo was able to meet the three evils who beat him up and left the Black Spark Lens to him. Later on, the ultimate battle begins in the ancient ruins. Daigo as Ultraman Tiga, who is supposed to be the warrior of light, must use his powers, however dark, in order to defeat the three evils.