Season 4 of Agents of S.H.I.E.L.D. has been unlike others that came before. Instead of telling one big story from premiere to finale, S.H.I.E.L.D. Season 4 has been split up into three story "pods." The first pod introduced Ghost Rider, and the second pitted the agents against L.M.D.s. The third story pod kicks off soon, and co-showrunner Jed Whedon has indicated that it may address the Season 1 plot that revolved around gravitonium, saying this:
We would not be doing our jobs as well as we could if we left that unanswered... We move so fast and we move past stuff, but when you get that thing that you care about called back to, there's a reward there that you deserve. For us, it's fun to play in that world. These were conversations that we were obsessed with and that we bent our minds into pretzels over two years ago.
Agents of S.H.I.E.L.D. first introduced the element gravitonium way back in the third episode of Season 1, when Coulson and his merry band of agents attempted to rescue the brilliant scientist Dr. Franklin Hall from kidnappers. Hall was trying to overload a gravity-distorting device powered by gravitonium before it could be used as a weapon; unfortunately, overloading the device would have destroyed an entire building full of people, so Coulson stepped in and destroyed it. Hall was sucked into the gravitonium, which was packed up and sent away to a S.H.I.E.L.D. facility with him still stuck inside. Jed Whedon's hint that we'll soon get another look at gravitonium may mean that we'll finally learn what happened to Franklin Hall.
If we do see Dr. Hall again, it's possible that he'll be a very different man. After being trapped in gravitonium for an indefinite period of time, Agents of S.H.I.E.L.D.'s Hall may look an awful lot like his Marvel Comics counterpart. In Marvel lore, Franklin Hall was the civilian identity of the supervillain known as Graviton, who has the ability to control gravity. He'd be a formidable foe to the good guys of Agents of S.H.I.E.L.D., and he would certainly raise the stakes for the third pod of Season 4.
Actor Clark Gregg also spoke to IGN, and he dropped this tease about payoffs for longtime fans in Season 4:
What goes down in the second pod, I would have to say so far has been so exciting, so mind-blowing. This sounds like spiel, but the construct that they've come up with, the pieces that were set up, did not prepare us for the way it was going to turn our entire world upside down and basically make the wildest fantasies you could have about using all the pieces that were set up in these first three seasons come true, and basically everything's in play. For the people who have been here since the beginning, you're going to see some stuff that only you can appreciate.
All things considered, it sounds like S.H.I.E.L.D. is going to be pretty fabulous for fans in the rest of the season. Sadly, Agents of S.H.I.E.L.D. is heading into a long hiatus before the third pod of Season 4 can kick off. Coulson and Co. return to primetime on Tuesday, April 4 at 10 p.m. ET on ABC. Check out our midseason TV premiere schedule to see what you can watch on the small screen in the meantime, and don't forget to take a look at our 2017 Netflix premiere schedule.
