出⽣台灣淡⽔⼩基隆（今新北市三芝）的橋間良⼦，是當年殖⺠地台灣⼈礦⼯⼯頭的女兒，於10歲時被養⽗楊添福作為童養媳帶來了沖繩⻄表島。她⾄今仍然守著當年⼀家⼈居住的房屋和養⽗⺟的墳墓。房屋座落鄰近如今已成為無⼈島、戰前曾是礦坑之島「內離島」的對岸——炭坑村「⽩濱」⼀處。⽽如今「⽩濱」已無多⼈居住。 年逾90歲的阿嬤，⼀個⼈守著這些秘密與那些說不出⼝的憤怒，寧願到死也不說出來。戰前礦坑時代的故事，島上⼈⼈聞之⾊變——這座位於台灣與沖繩之間的邊陲⼩島，荒島上藏著屍骨的海上洞窟與亂葬崗、困在紅樹林之中的炭坑村，以及熱帶叢林中礦坑設施的廢墟，都藏著那些不願意被訴說的礦坑幽魂。礦坑裡到底發⽣了什麼事？她的養⽗楊添福招集了無數台灣礦⼯來到「綠⾊牢籠」，究竟她的養⽗在⼤⽇本帝國主義下扮演了什麼樣的⾓⾊？ 我們跟隨阿嬤的晚年故事，走進邊陲島嶼的綠⾊叢林中，已成為廢墟的礦坑及被埋藏的⼈⽣回憶。透過紀錄片，回到阿嬤的記憶深處那個曾經如溫暖午後的台灣，試圖述說出⼀個充滿暴⼒、輝煌與無奈，卻被世⼈遺忘與忽略的瘋狂時代，以及那⼀顆無法挽回過往的悲傷⼼靈。

There remains only silence in the "Green Jail," the once upon a time large-scale mining village located on Iriomote Island, Okinawa, Japan. Before World War II, under Greater East Asia Imperialism, "Green Jail" imprisoned thousands of miners. These miners were from Kyushu, and other places of Japan, as well as Japanese colonies: Taiwan and Korea. The miners who were forced to work there, many of whom also contracted and died from malaria. As for the "Taiwanese miners," the morphine injection was prevalent so that they could work nonstop day and night. Grandma Hashima, now 92 years old, is the adopted daughter of the Taiwanese head miner, Yang Tien-fu. With hardly any visitors, grandma lives alone in an old and shaggy wooden house by the "jail on the sea" where her family once lived, she recounts her experience of the coal mine days on the island. What happened in the coal mine? Grandma's adoptive father, who recruited hundreds of Taiwanese miners to "Green Jail," knowing or not they could never return home... Was he an oppressor or the oppressed victim of Japanese Imperialism? Through her memories of guilt, pain, anger, and the miseries of the past 80 years, this film also portrays the last years of Grandma Hashima's life.