无影无踪 without a trace
Explanation
形容人或事物完全消失，不知去向。
Describes people or things that have completely disappeared and whose whereabouts are unknown.
Origin Story
话说唐朝时期，有个侠客名叫李寻，武功高强，行侠仗义，深受百姓爱戴。一日，他听说远方有一伙强盗横行霸道，残害百姓，便只身前往，准备除恶扬善。他一路追踪，翻山越岭，终于找到了强盗的巢穴。然而，当他潜入巢穴时，却发现强盗们早已逃之夭夭，只留下空空荡荡的营帐和散落的兵器，所有强盗都无影无踪了。李寻四处寻找，却没有任何线索，强盗们仿佛人间蒸发了一般。虽然这次没能抓到强盗，但李寻并没有灰心，他相信正义终将战胜邪恶，他会继续寻找强盗的下落，将他们绳之以法。
In the Tang Dynasty, there was a knight named Li Xun, who was known for his exceptional martial arts skills and his commitment to justice. One day, he heard of a band of robbers who were terrorizing the people in a distant land. He set off alone to eliminate the evil. After a long and arduous journey, crossing mountains and valleys, he finally found the robbers' lair. However, when he infiltrated the lair, he discovered that the robbers had already fled, leaving behind only empty tents and scattered weapons. All the robbers were gone without a trace. Li Xun searched everywhere but found no clues. The robbers seemed to have vanished into thin air. Although he failed to catch the robbers this time, Li Xun did not give up hope. He believed that justice would prevail, and he would continue to search for the robbers and bring them to justice.
Usage
多用于形容人或事物消失得无影无踪，不知去向。
Used to describe people or things that have disappeared without a trace and whose whereabouts are unknown.
Examples
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他消失得无影无踪，如同人间蒸发了一般。
ta xiaoshi de wú yǐng wú zōng,rútóng rénjiān zhēngfā le yībān.
He disappeared without a trace, as if he had evaporated from the world.
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那伙盗贼作案后，便无影无踪了。
nà huǒ dàozéi zuò'àn hòu,biàn wú yǐng wú zōng le.
The gang of thieves disappeared without a trace after committing the crime.