Spoiler warning and idle speculation for Batman #667-668.
One of the pleasures of the current Batman storyline is that it invites heavy reader involvement. Grant Morrison and J.H. Williams III don't just ask us to identify all the art homages, they practically demand that we develop theories and search for clues to the identity of the Black Glove--even though they haven't really written a mystery at all.
So, who is the Black Glove? Is he part of a Club of Villains, or is he just impersonating the Club of Heroes' foes? Is he one of the Club of Heroes? Or is he posing as one of the heroes after killing and replacing them? That was certainly Wingman's theory, but then Wingman himself made a great red herring because he was such a jerk. You were probably hoping he turned out to be the killer right up until he turned up as a victim... assuming that really was the Wingman hanging there, his face burned beyond recognition. Perhaps he just created his own alibi? But then who did the body belong to? The great thing about this theory is that it makes Williams' flashback images part of the misdirection--they would be showing us the wrong character! But why should we assume these extradiegetic images are honest and accurate clues?
The Knight has been behaving oddly--when did he disappear, and why was he waiting around inside the locked library instead of getting help? But he's being set up too obviously (although, in a better set-up, the red herring wouldn't have that bomb in his belly). Batman has already discounted the possibility and, stepping outside the text for a minute, it seems unlikely that Morrison would corrupt a character after investing so much work and affection in him. And where would that leave Beryl?
Suspicious coincidences are settling around the Dark Ranger. He keeps running off on his own, Red Raven disappears (apparently getting captured) after vowing to follow him, and that full-face mask means anybody could be wearing the suit at any point after he wanders off at the end of his initial appearance. The Ranger could have been the first hero to die; his combat boots do look a lot like the pair we see standing over the fallen Legionary.
Maybe we shouldn't read too much into such incidental details. Nothing can motivate Morrison to produce a meticulous, detail-oriented script like a top-notch artistic collaborator--Williams is at least the equal of Phil Jimenez and Frank Quitely in this regard--but the parts don't always line up. At the beginning of #668 the Knight has disappeared and become a prime suspect in the killings, yet at the end of #667 he ran outside with the others and was standing by their side just before the Legionary was killed. Not visible in that scene: the Dark Ranger, Wingman, and Man-of-Bats. But does that mean anything?
The Dark Ranger has some curious absences and reappearances in this issue. But does that mean anything? Wingman's body turns up in a room that's already been locked and broken into and re-sealed once before; the house must be so riddled with secret passages that no character movements can be sufficient evidence in and of themselves. And we know so little about most of these characters that nearly any of them could turn out to be the killer--Morrison has insured we won't learn about the breakup of the Batmen of Many Nations (and hence the likely motive for whatever revenge transpires here) until the final chapter.
From the brief flashback we get this issue, we know that John Mayhew has something to hide, some "grave news" that prompted the Club of Heroes to disband. But he was killed in the first issue, wasn't he?
Maybe. We see something that looks like his face, and the Black Glove says he killed Mayhew, but how much should we trust him? Or does "John's dead" signal the death of an old identity, a discarded personality? A movie director could easily work up (or pay someone to work up) a false face that looks real enough for a short video. And that body dangling on page 1 of #667--sure, that looks like Mayhew, but is that a moustache or a shadow thrown by the weird lighting? Other odd details from that issue: a picture of Mayhew posing in front of a race car, with almost exactly the same uniform and posture as the Dark Ranger on the previous page; and that "Black Glove" poster, of course. Even if Mayhew is dead it seems likely he had something to do with the Black Glove's creation, making him a victim of his own ennui.
If this were a fair-play locked-room mystery, I'd guess that Mayhew either is the Black Glove himself (possibly posing as the Dark Ranger), or he inadvertently created the Black Glove when he approached someone else to help him set up a murder mystery for the Club of Heroes reunion--possibly either the Dark Ranger or the Wingman, who killed the Ranger and switched costumes with him at some point while the other heroes were preoccupied with the Knight. (Plus, making the Dark Ranger and/or Wingman the Black Glove's guises/accomplices would be a none-too-subtle way of repudiating the grim and gritty Batman both men have imitated, and Morrison's been all about that lately.)
But the story may not be a fair-play mystery, and the walls of the Mayhew mansion are so porous that "locked-room" is a misnomer. This is a suspense story, set in a private little paradise turned hell where evil becomes so palpable it distorts panel borders, or becomes them, drawing the heroes into its tightening grasp.
We may not be able to figure out the Black Glove's machinations until they're over, but that's all right. Watching them unfold is half the fun. Watching Morrison and Williams deliver them, and trying to guess where they're going next, is the rest.