Naturally, Narita can't just do a short story collection. He's got to pull a Kadono, and have all the stories taking place at the same time. I wound up being pretty glad I read this right after the anime helpfully reminded me who some of the characters were; he clearly wanted to give some people who haven't played an active role in a while something to do.
On that note, the first story starts off with Namie and Mika having an epic bitch off; this eventually involves Namie dousing Mika with an immobilizing drug and attempting to pour acid on her face, while Mika cheerily reveals that she's got the entire cast's apartments bugged and their computers hacked and knows everything going on everywhere. Seiji eventually steps in and settles things as only he can.
Second story was probably my favorite, since it was cheerily out of Narita's comfort zone again; focusing on Akabayashi, one of the yakuza characters introduced in the last volume. He's such a monumental bad ass that he gets stabbed in the eye by Saika, rips his own eyeball out to stop the blade from infecting him, and falls in love with Anri's mom, who was wielding the sword at the time. All of which is a flashback woven through the story of how he uses his own Dollars membership to manipulate a bunch of low level drug dealing thugs into taking out a yakuza group that's trying to kill him.
Third story is probably the most typically Narita; as the rumors about Shizuo's activities in the last few volumes spiral dramatically out of control, a group of his victims somehow becomes convinced that Shizuo has a wife and kid, and tries to kidnap them...only to get the shit kicked out of them when the wife turns out to be the Russian assassin (now working with Toma and Shizuo) Izaya's crazy ass sisters, and yakuza kid Akane, who is still carrying around a stungun.
There's also a brief romantic interlude with Celty and Shinra, constantly interrupted by phone calls from characters in all the other stories, and a framing sequence in which Izaya, in the hospital, is visited by one of the suicidal girls he was toying with in the first volume (a bit they wound up not putting in the anime, since he drugged her and put her in a suitcase just to fuck with her head.)
And volume eight's out in June. And a new Baccano came out yesterday. It never ends!