dagger; ladle; ancient type of spoon

(lit.) the assassin's dagger, concealed in a map scroll, is suddenly revealed when the map is unrolled (referring to the attempted assassination of Ying Zheng 嬴政[Ying2 Zheng4] by Jing Ke 荊軻|荆轲[Jing1 Ke1] in 227 BC) (idiom); (fig.) malicious intent suddenly becomes apparent

see 圖窮匕見|图穷匕见[tu2 qiong2 bi3 xian4]