the handwriting on the wall(North American English)
(also the writing is on the wall, see the writing on the wall)
(saying)used when you are describing a situation in which there are signs that something is going to have problems or that it is going to be a failure(看出)厄运临头的预兆,不祥之兆
It is amazing that not one of them saw the handwriting on the wall.令人惊讶的是,他们中没有一个人看到墙上的笔迹。