Does a comma belong here? If so, where?

"...perhaps one, or a series of events that shaped her future?"

vs. "...perhaps one, or a series of, events..."

My question is whether a comma belongs in a sentence such as this one. I'm not sure how to explain this very well, since it's always hard to define and describe English grammar concepts even if you know how to apply it, but basically, in the above sentence there are two possible scenarios: one event that shaped her future, or a series of events that shaped her future.

I know this might not even be grammatically correct at all because if you take out the second part, it ends up being 'one events', which is ungrammatical, but I thought I'd ask about it anyway.

"...one, or a series of, events" -- It seems awkward to put a comma at the end of 'of', but at the same time, it seems wrong not to use a comma to signify the end of that idea. My knowledge of commas tells me it is okay to use them to interrupt a thought and inject something relevant into it, like so: "We believe that Katie, with her background in flute, would do better in classical music than in jazz." Here, "with her background in flute" is separated from the rest of the sentence by commas.

Does the same apply to the first situation? Or would there be no 'final' comma?

Thanks in advance!