méng zài gǔ lǐ
variant of 蒙在鼓裡|蒙在鼓里[meng2 zai4 gu3 li3]
朦
méng
used in 朦朧|朦胧[meng2 long2]
在
zài
to exist; to be alive
鼓
gǔ
drum
里
lǐ
li, ancient measure of length, approx. 500 m