Season 2 Spike goes to hell instead of Angel to close Acathla

I'm looking for a fic I read ages ago where Spike accidentally gets sucked into hell instead of Angel to close Acathla (but not the one where Spike chooses to sacrifice himself - this is an accident). I THINK it turns out that Willow's soul spell was too good and Angel got his real soul back which doesn't prevent him from doing evil stuff. And I think Spike comes back feral. Any ideas?

Becoming Undone ------ by spikeslovebite

http://dark-solace.org/elysian/viewstory.php?sid=74

Instead of leaving Buffy to fend for herself against Angel and Acathla, Spike comes back to lend a hand and gets sent to hell in Angel's place. Riddled with guilt and plagued by dreams, Buffy becomes obsessed with making things right. Will she get her chance when a feral Spike is returned from hell, or will she get something... 'a whole lot better'?

Shadows babe
That's the one - thank you ))

Ooooh I'm gonna read this one, it sounds good!!