Darkling?
In case you're wondering, the exact phrase occurs in the following speech:
For, you trow, nuncle,
The hedge-sparrow fed the cuckoo so long,
That it's had it head bit off by it young.
So, out went the candle, and we were left darkling.
The fool says it in Act 1, scene 4. That's all I'm going to tell you. You'll just have to read the whole darn play. You can find it here.