Daily Chinese Idiom Guessing Game
To be completely indifferent or unmoved; to show no emotional response.
衷内心。心里一点儿也没有触动。指对应该关心、注意的事情毫不关心，置之不理。
清·李宝嘉《官场现形记》第三十三回以至顶到如今，偏偏碰着这位制军是不轻容易见客的，他见也好，不见也好，便也漠然无动于中了。”
He listened to the tragic news with utter indifference, completely 无动于衷.