The Agents of SHIELD are hopping back on the Bus as filming begins for season 2.

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Director Coulson (Clark Gregg) and his agents need to rebuild SHIELD from the ground up, and the team started their long journey back to international prominence on Thursday.

"First day of S2 in the can," Coulson tweeted on Thursday. "Headed to [San Diego Comic-Con] where I never have ANY fun..."

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Marvel keeps a tight lid on all their productions, but Gregg, Ming-Na Wen (Agent Melinda May), Elizabeth Henstridge (Agent Jemma Simmons), Iain De Caestecker (Agent Leo Fitz), and Brett Dalton (Grant Ward) may drop a few hints about season 2 when they drop by Comic-Con on Friday.

Or not, according to series co-creator Maurissa Tancharoen.

"Tomorrow, we'll talk about a whole lotta nothing. Marvel's orders," Tancharoen wrote before leaving for Comic-Con on Thursday. "Ballroom 20, 3pm. See you there."

When Agents of SHIELD does return to ABC this fall, Coulson's team will need to deal with HYDRA, the ill effects of GH-325 (see video below), Skye's mysterious parents, and the reemergence of Grant Ward.

Find out more when Agents of SHIELD premieres Sept. 23 at 9 p.m. ET on ABC.