Bizarre Light shining through the middle of my image

I’m working on a fluid/smoke tutorial and during this rendering, I had a strange light beam in the middle of the image. The only light is off to the side and above, and the only pieces are a fluid domain, a smoke domain, a fluid emitter, a smoke emitter, and an obstacle.

The video in the tutorial did not have this problem.

Here’s my render:

Please ALWAYS attach or post a linkto your blend file. Your rendered image on its own is all but worthless in determining the specific cause of the problem.

If you say you’re following a tutorial why not tell us which one, give the url.
Also tell us what version of blender you are using and build number if not an official release and operating system/graphics card and drivers. What renderer are you using, if cycles whether cpu/gpu etc etc

I see a vertical rounded shape that looks to have a bottom to it, like a medicine capsule, but do bear in mind that, when you start getting into the world of compositing, a “white spot” on an image does not have to be coming from a light source. It could simply be that you’re combining the data in the wrong sequence … e.g. putting in front what should be in back, or applying a modifier to the wrong channel of data. The “view” node, and background-image, is a great way to debug this sort of thing. (And “debug” is exactly what you are doing.)