At long last, the Strategic Homeland Intervention, Enforcement and Logistics Division is back open for business.

Tonight sees the return of "Marvel's Agents of S.H.I.E.L.D." after several months off the air, plunging viewers back into the world of spies and shadows where guys like Agent Phil Coulson thrive. But a lot has changed since the show first began, thanks to a tumultuous first season that resulted in some major deaths, betrayals and organizational overhauls.

Here's what you need to know about where things stand on "Agents of S.H.I.E.L.D.," ahead of tonight's premiere:

HYDRA Killed S.H.I.E.L.D.

The game-changing reveal of "Captain America: The Winter Soldier" had massive ramifications on "Agents of S.H.I.E.L.D.," resulting in the agency's total shutdown.

The New Man in Charge

Well, not a total shutdown. By the end of season one, a presumed dead Nick Fury resurfaced to pass the torch to Phil Coulson, anointing him as the new director of S.H.I.E.L.D. Of course, there's the not-so-small matter of having to rebuild the agency from scratch, but that shouldn't be more than a bump in the road for a man who cheated death, right?

The Writing on the Wall

Not only must Coulson rebuild S.H.I.E.L.D., he also has to deal with some cosmic qualities he started exhibiting at the end of season one. Much like his late friend-turned-foe John Garrett, Coulson was last seen writing mysterious markings on windows. What these markings mean, and why Coulson's making them, is a complete and total mystery — probably even to Coulson himself.

The Skye May Rise

As he puts S.H.I.E.L.D. back together, there are only so many people Coulson can trust. From the old guard, there are a few reliable faces, including Melinda May, though her friendship with Coulson needs some work after some Nick Fury-related secrets; and Skye, the computer hacker who joined Coulson's squad not so long ago. Early looks at season two show Skye as a more confident, gun-toting badass, indicating that she's doing well under May's supervision.

World Ward Two

Grant Ward, the steel-jawed agent who crushed on Skye throughout season one, turned out to be a dirty rotten scoundrel, working for HYDRA right under Coulson's nose. Now, he's rotting away in prison, bearded and alone. With Brett Dalton still on board as a series regular, it shouldn't be long before Ward finds his way back onto the Bus, in some shape or form.

Throwing Fitz

Also missing from the squad: Fitz, the bright-eyed scientist who sacrificed his life to save Jemma Simmons from drowning. At least, he sacrificed his consciousness. Fitz remains in a coma after putting himself in harm's way to save the woman he loves, but at least he's still alive — and yet, it's worth wondering if he'll ever wake up again.

The New Kids in Town

When season two premieres, we'll see a few new faces in the mix. New to the cast is actor Nick Blood, who plays a sharp-shooter named Lance Hunter. Also on board is "Xena" and "Battlestar Galactica" veteran Lucy Lawless as agent Isabelle Hartley, a veteran of S.H.I.E.L.D. and one of few people from the good old days that Coulson can trust.

Evil on the Rise

With new heroes come new enemies, including Brian Patrick Wade as Absorbing Man, a famous "Hulk" villain from Marvel Comics. There's also "Dollhouse" alum Reed Diamond on board as a HYDRA agent named Daniel Whitehall. And perhaps most terrifyingly of all: Kyle MacLachlan has joined the cast as Skye's mysterious father, who will hopefully be able to explain why his daughter is an 0-8-4.

Agents of the Past

Finally, keep your eye out for an appearance from Peggy Carter and the Howling Commandos, most prominently featured in "Captain America: The First Avenger," and set to resurface later in the year when "Agent Carter" premieres. We'll get our first glimpse at Hayley Atwell back in action as the awesome Peggy when "S.H.I.E.L.D." premieres tonight.

Are you looking forward to the new "Agents of S.H.I.E.L.D." season?