For most (if not all, I haven’t looked at every one in detail) of the episodes, there are pretty in-depth (almost scene-by-scene) recaps given on the Fandom wiki for the show (https://the100.fandom.com/wiki/Episode_Guide). I’m putting a little more effort into other pages right now, but if anyone wants to help, it has a CC-BY-SA license, so copying them verbatim should be okay. If I’m wrong about any of this, someone please correct me - I’m rather new here.