After padding out the climax of its last major arc with some more light-hearted fare in its previous volume, we return our attention to an all-new plot as this fourth volume of the series commences - although when I say "new", this particular story actually slots neatly into a major storyline from the (unreleased outside of Japan) series from which this manga spins off, A Certain Magical Index.
With normality restored to Academy City following the "Level Upper" incident, everything seems to be peaceful enough in the world, even if narrow short-cuts around the city are suddenly teeming with people for some reason, much to Kuroko's frustration. It doesn't take long before we find the reason behind so many people suddenly taking unorthodox routes to go about their business - someone has been leaving cash cards hidden in normally unused locations around the city containing various amounts of money; a situation that has unsurprisingly given rise to a "treasure hunt" of sorts as news about money being strewn around the city travels fast amongst its residents.
When a mixture of being dragged around the city by Saten, idle curiosity and blind luck combine, Mikoto Misaka finds herself on the trail of the generous culprit who has been leaving these cash cards laying around - but what is this person's goal exactly? The truth appears to be closer to home than Misaka could comfortably imagine, as rumours about her being the centrepoint of an experiment in cloning espers with her ability and skills well and truly come back to haunt her. Even when Misaka herself seems to have put any worries surrounding those rumours to rest, she soon finds herself face to face with... herself?
Having already impressed us to various degrees within its first three volumes, this fourth instalment of A Certain Scientific Railgun is an almost perfect example of everything that makes this series so enjoyable. Here is a manga which has no qualms about employing comedy, even in the midst of some action or otherwise important moments of plot progression, but it also knows when to knuckle down and focus on what's going on when it really comes to the crux of its story - witness the brutal ending to this volume which leaves us cruelly hanging and waiting for the fifth volume to arrive in a few months time.
All of this is backed up by the continuing expressive quality of the manga's artwork, which is clean, clear and largely rather adept at being both attractive when it wants to be but visceral and violent when required of it - throw in a solid translation from Seven Seas Entertainment (although our copy did have one very slight printing error on a single page, for reference) and there's nothing to get in the way of drawing you into this series.
Drawn in is exactly what you'll be by this volume too - it was almost literally impossible to put down until I'd read it cover to cover, as it revealed its story in a compelling mix of light-hearted and entertainment and darker, more sinister plotting. This is undoubtedly the high point of an already enjoyable series so far, and I for one will be waiting impatiently to see where it goes next.