I found "Always Valid" after my earlier Lightbox plugin stopped working for some unknown reason. After trying about a dozen other more cumbersome plugins that didn't work, AV did. Great.
Now if I could only figure out why it's putting "undefined" beneath every photo. I have "alt" text defined in my photos. Some usage examples would be helpful by the plug installs with no usage examples.
(PS: Figured it out. Replace "alt" with "Title" [or use both].)