Volcano...

I hadn't seen it (or heard it mentioned) before either, although I missed the latter part of season 4. I think they're running out of ideas.

Also, I think they're lacking someone with chemical knowledge. Humphrey picks up a container labelled "phenolphthalein" and pronounces the name with the primary stress on the second syllable, rather than the third, which is the way we pronounced it in my chemistry days (and the way all my dictionaries pronounce it). Mind you, he did imply that his chemistry knowledge was a bit rusty. Or perhaps he's been influenced by the way some people illogically pronounce "kilometre/kilometer" with the stress on the second syllable.

I can't recall the volcano appearing before. I understand that the series is filmed in Guadaloupe and Googling "Guadeloupe volcano" leads to a number of images that I can't match to the one in the recent episode. Possibly CGI?

When I heard about the volcano, I was thinking straightaway about the episode (5.04) where Dwayne's friend died and then Dwayne got a text that said 'I was murdered'.

I had the impression that the original accident, that happened many years before, happened on a mountain(/volcano?) too. I was somehow not surprised it was there.

It's been a while since I saw it though, so I could be wrong about the location in the other episode.