in one's hands; in one's control
優勝を手中に収めた。
I secured the championship.
彼の手中にある情報は非常に価値が高い。
The information in his hands is extremely valuable.
全権限が社長一人の手中に握られていることが問題だ。
It is a problem that all authority is concentrated in the hands of the company president alone.