By introducing its own particular spin on a story whose origins lie in A Certain Magical Index (the light novel series from which this manga spins-off), the fourth volume of A Certain Scientific Railgun was a notably superb instalment in a series which hasn't exactly been short on quality even before that point.
More importantly for this particular review, the previous volume of the series left us with a horrific yet delicious cliff-hanger, as the revelations which so surprise protagonist Mikoto Misaka surrounding the use of her DNA to create a (decidedly oddball) army of clones turned sinister as the true nature of their use was revealed - to serve as cannon fodder for another incredibly powerful resident of Academy City in the hope that his constant encounters with the Misaka clones would prove to be the secret to unlocking the so-called "Level 6" of esper powers.
For Misaka's part, she's having none of this - not only does she want to put a stop to the programme which is so recklessly using her genes, but her more immediate concern is protecting her "other" self from being obliterated by her opponent. Given the abilities of that opponent this proves to be nearly impossible, but luckily for Misaka circumstances ensure that she lives to fight another day, allowing her to turn her attention to destroying the multitude of locations employed in the nefarious research using her clones. Although her powers and perseverance look likely to make short work of blowing the heart of this research to smithereens, those involved in the project aren't about to let their research go up in flames quite so easily and hire some decidedly tough customers to "handle" their problem.
The result of all this is easily the most action-packed volume of A Certain Scientific Railgun yet, comprising of effectively cover-to-cover esper-based battling - and it's absolutely incredible stuff that is simply impossible to put down, to the point where I delayed other plans to finish the volume in a single sitting. The pace, flow and tension of this action is nigh-on perfect, the newly introduced underworld "fixers" who debut in this volume are good characters in their own right as well as powerful adversaries, and the whole story is wrapped in a layer of polish which makes every panel a joy to both read and look at. Even when the volume takes a breather via its little inter-chapter gag panels (and boy do you need one in the midst of all the gripping goings-on), or even more notably courtesy of a number of four-panel comedy manga strips at the end of it all, this volume doesn't put a foot wrong - some of these strips are so hilarious that I get the feeling this series could support a four-panel comedy spin-off in its own right.
Try as I might to find fault with this volume I simply can't do it, as it demonstrates expertly the essence of what a good manga series should be about - great characters, a fascinating scenario backed up by an incredibly strong and gripping story and excellent artwork which looks great and advances the story in a clean, considered fashion. With a good translation and overall treatment from Seven Seas Entertainment, this is tantamount to perfection on the printed page. The only downside is that this series can't possibly get any better moving forward... can it?