As A Certain Scientific Railgun S gets its teeth into its first proper story arc after last week's introductory episode, we begin with a flashback to Misaka's youth, and a promise made to doctors to allow them to map the young Railgun's DNA in the same of advancing medical science.
This incident from many year's previously is little more than a distant dream for our present-day Misaka however, as she has other things to contend with - Kuroko's advances for example. Indeed, it seems that even a shopping trip can't be a regular event for Mikoto, as she and Shirai come across a cash card left hidden in a small alleyway, something which has been happening with a strange regularity around Academy City to the point where it's become an urban legend that people are actively hunting for, not least Saten of course.
Any semblance of a normal day is really put to a halt for Misaka when she overhears some ruffians discussing the possibility that they've discovered the source of the person distributing the cash cards - something which they want to use to their advantage by pinching the lot, of course. Misaka is having none of this, and so tails them with a view towards bringing their nefarious plan to a halt while also finding the person responsible for hiding the cash cards - then again, it seems that the culprit has no problems in dealing with a bunch of unskilled thugs herself...
After that pretty rip-roaring anime original opening episode, we're now well and truly on the track of a "proper" story arc - I'll be the first to admit that some of its attempts to push the plot forward are a little clumsy (especially the heavy-handed hints about cloning - why not be more subtle about it rather than spoiling your own story for newcomers to the franchise?), but as a whole this was a pretty solid episode which again blended its elements well to make for a satisfying setup for what is to come overall. Of course, perhaps it's easier to say that as a reader of the original manga, so it would be interesting to see what those unfamiliar with the source material make of it.