如果某人 in the palm of your hand, 那你就完全的管控了此人。

例句

Elvis Presley was a great performer; he had the audience in the palm of his hand.

Joan knew all her neighbours' shameful secrets. She felt they were in the palm of her hand.

请注意

短语 give someone a hand 的意思是帮助某人。

I know how to operate this machine. Let me give you a hand.