Why does she use こと at the end?


> 今は、依頼人を助けるための「情報」を聞き逃さないこと。

I understand the sentence but I don't know why she uses こと at the end.

[![Ace
Attorney](https://i.stack.imgur.com/13YLH.png)](https://i.stack.imgur.com/13YLH.png)

