(deyim) The writing on the wall (or sometimes 'handwriting on the wall') is an expression that suggests a portent of doom or misfortune. It originates in the Biblical book of Daniel—where supernatural writing fortells the demise of the Babylonian Empire, but it has come to have a wide usage in language and literature
This nuclear plant is about to explode, I think, the chief engineer said. We'd better get out of here in a hurry, the handwriting is on the wall.