居心叵测 (jū xīn pǒ cè) | Meaning: harboring unfathomable motives (idiom) | Chinese Idiom with Pinyin & Origin

(lit.) human face, beastly heart (idiom) · (fig.) mild in appearance but malicious in nature人面兽心rén miàn shòu xīn

words of a Buddha, heart of a snake (idiom); two-faced · malicious and duplicitous佛口蛇心fó kǒu shé xīn

to have an ulterior motive (idiom)别有用心bié yǒu yòng xīn

treacherous · sinister阴险yīn xiǎn

evil tactics · devilish stratagem · malicious intrigues · underhanded tricks鬼蜮伎俩guǐ yù jì liǎng

(idiom) to harbor evil intentions; to conceal malice包藏祸心bāo cáng huò xīn

harboring unfathomable motives (idiom)