孤军深入

Explanation: Isolated deep into the enemy's army combat zone. 　　Source: "Zhou Shu He Ruodun Biography": "Zhen, etc. to London alone in-depth, just about to put the rules." 　　Examples: Jin ~, teachers, and your late matter to hit the West Division. ("Biography of Sung kind of world value.") Thesaurus:  start a solo run, Zhi-Yong complete in both respects, high and dry, insulation helpless