(one's) life is in (someone's) hands

One's life, livelihood, or well-being is at the mercy and discretion of someone else. Please, doctor, you're the only one who can repair the damage to our daughter's heart. Her life is in your hands! We've transferred all of our savings over to be put into the investment. My family's lives are in your hands now. Sir, help me, please! Pull me up the cliff—my life is in your hands!

your life is in someone's hands

If your life is in someone's hands, they have complete control over whether you live or die. The realization that another woman's life may be in my hands is a frightening one. Note: You can also say that you put your life in someone's hands or that someone holds your life their hands. What makes you think I would put my life in your hands? You feel a responsibility to people because sometimes you're holding their life in your hands.