Cage of Nightmare is a Manga/Manhwa/Manhua in english language, Manhua series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Huang Liang and his sister Nan Ke are orphans of unclear/obscure origins. Since childhood, they had been plagued by weird/strange nightmares. After a secret experiment conducted with her instructor/teacher/academic advisor, Nan Ke became a human vegetable. The sudden disappearance of his sister, the interminably repeating and extending spaces/dimensions, the deranged/chaotically, twisted monsters… … While investigating the circumstances behind the experiment, Huang Liang encountered a series of matters beyond the boundaries of understanding. And behind these strange things seemed to lurk some sort of earth-shattering secret…