The threads of DC Comics’ Rebirth mystery were picked up again in last week’s Batman #21, but very little investigative ground was actually covered. The bulk of that issue was an absolutely brutal fight between Batman and the Reverse-Flash, ending in the latter’s death (though not by Bruce’s hand). Batman #21 was little more than a tease for what is to come, deepening the mystery surrounding the Rebirth event and, of course, that smiley face button.

On a larger scale, “The Button” mini-event teases that big changes are ahead for the DC Universe, hinting at a potentially groundbreaking reversal of the New 52 and a return of much of the DC Universe’s storied history. The Flash #21: The Button Part Two doesn’t yet reach that point, but ending up there now seems a foregone conclusion. If DC Universe Rebirth#1 implied that all which was erased by the New 52’s “clean slate” would come back, then The Flash #21 pretty much confirms it.

Picking up in the moments where Batman #21 left off, The Flash #21 begins with Barry Allen doing what he’s best at — deciphering a crime scene. Batman may be considered the World’s Greatest Detective, but it’s Barry who makes his living investigating crime scenes. There’s no one better equipped to investigate this mystery — something which writer Joshua Williamson makes abundantly clear with Barry’s detailed running monologue.

In the opening pages, Barry is already piecing together Thawne’s sudden and unexplained death, Wally’s equally unexplained return (found in DC Universe Rebirth #1), and how it all ties into that button. He certainly hasn’t come close to deducing who could be behind everything, who is God with the capital-G, but he’s on the right track. In that respect, so is “The Button”, with Part Two being a far more satisfying comic than Part One. That Batman/Flash team-up teased by many a solicit for “The Button” finally happens in this issue, making it a more engaging tale than the Batman/Reverse-Flash fisticuffs. Part of the allure to Rebirth is re-establishing history between characters, re-uniting long lost friends, and The Flash #21 manages this with something as simple as Bruce and Barry working the same case.

The Flash #21 doesn’t bother with heavy Watchmen allusions in either its story or art, and the issue is all the better for it. Not to suggest there’s no symbolism to be found, on the contrary, “The Button Part Two” is chocked full of references — both subtle and overt — to the 70+ year history of the DC Universe. There a few choice panels which fans will be pouring over for clues as they feature hints at what stories and characters may have already returned to the DC Universe. Then there’s Batman and Flash’s journey into the Speed Force itself, complete with short glimpses at important events from the DC Universe’s past. Those looking for confirmation that landmark events — such as DC’s many Crisises — are indeed back in canon, look no further.

Howard Porter’s artwork proves the perfect match for this comic, clearly rendering what are heavily detailed panels — especially inside the Batcave and the Justice League’s Hall of Lost and Found. That eye for detail isn’t lost on characters, either, bringing for strong emotions from both Batman and Flash. Porter also handles The Flash’s speed in a unique manner, making the speedster’s lightning quick movements transition fluidly from page to page. Along with bold colors from Hi-Fi, the artwork of The Flash #21 isn’t evoking the same visceral response as that of Batman #21, but it isn’t meant to. Williamson and Porter are crafting a real mystery, and there are hints scattered throughout. For instance, while within the Speed Force, does that blue membrane imply there’s more going on here than just another trip through the multiverse?

Where Batman #21 felt like a tease in the worst way after waiting the better part of a year to return to the Rebirth mystery, The Flash #21 begins laying out the evidence. Its cliffhanger (because of course there’s a cliffhanger) is predictable, but it still feels exciting. For fans who’ve stuck with DC Comics through Flashpoint, the New 52, and Rebirth,”The Button” promises to be one heck of a story. Now, let’s see if the final two-parts can deliver on that promise.