A dagger revealed in an unrolled map
When the truth is revealed at the end of some event
Neutral
他的诈伪终于图穷匕见，大家不禁因此不寒而慄 | Tā de zhàwěi zhōngyú túqióngbǐxiàn, dàjiā bùjīn yīncǐ bùhán'érlì
After his trickery was finally revealed, everyone couldn't help but shudder with fear
[Source]
None
图穷匕首见 (tú qióng bǐ shǒu xiàn)
Note that for this chengyu, 见 is pronounced as "xiàn," not "jiàn"
《战国策》(Zhàn Gúo Cè, Strategies of the Warring States), a work which chronicled the Warring States Period (475 - 220 BC)
At the end of the Warring States period (475 - 221 BC), the state of 秦 (Qín) was rapidly growing in strength. It had already conquered the states of 韩 (Hán) and 赵 (Zhào), and the prince of the state of 燕 (Yān) knew that troops were currently on the way to invade his land next. In efforts to fend off the invaders, he decided that he would hire someone to assassinate the 秦 leader 赢政 (Yíng Zhèng, later known as the first emperor 秦始皇 (Qín Shǐ Huáng)). This someone was a man named 荆轲 (Jīng Kē).
In order to ensure that 荆轲 could get close to the 秦 leader, the prince procured two items for him. The first was the head of a high-ranking soldier who had deserted the 秦 army, and the second was a map of a region that the 秦 king strongly desired. 荆轲 took both of these items, and when he took the map, he placed a dagger at the bottom and carefully rolled up the map so the weapon could not be seen. He then set out on his mission.
When 荆轲 arrived to see the 秦 leader, the two items were enough to guarantee him an audience. When it came time to present the map, 荆轲 politely did so, and when the king unrolled the map, the concealed dagger became visible.
At this, 荆轲 seized the knife and the sleeve of the king and tried to slash at him. The king, however, was able to pull away and unsheathe the sword he carried upon his back. He started hacking 荆轲 into pieces, and guards finished the assassin by beheading him.