A good opening line is absolutely crucial to a story. It needs to be memorable and grip the reader, thus encouraging them to continue reading. It needs to have a sense of drama, and set the tone for the following story.
Then opening line should encapsulate the emotions you want your reader to feel in that moment. It also needs to relate to the first character to appear on the scene, and finally, it should give some hint at the setting too. Yes, all of that, in one sentence. It can be done, and you will feel amazing when you do it.