Is this a virus infection? Are they goners?

That's a sad image Betsy . Joshua @Australis - Have you seen anything like this before?

Unfortunately I've never seen anything like that before.

Did this happen suddenly and is this the only plant affected?

Been like that for few works and only ones affected. There are other irises in the bed.

It's possible that it could be mosaic virus infection since only one plant is affected. I would dig it up and keep it isolated or discard it and replace it with a new specimen. It can be tested for that, but it's often more expensive to do the test then it is to discard and replace. It spreads via insects, not directly from one iris to another. There's a thread on here about it if you want to dig it up. There's pictures on the internet too compare to.
https://images.search.yahoo.co...

@tveguy3, Thks Tom.

I would want it entirely gone from my garden. Sucking insects can also fly, so you can't really quarantine the affected plants.