Agents of SHIELD will uncover Coulson's mysterious city in just two episodes.

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Unraveling the mystery of Coulson's (Clark Gregg) alien gibberish took the first half of season 2, but now that they know what they're looking for, the SHIELD team will find have little trouble decoding the cartographical puzzle in "...Ye Who Enter Here."

Fortunately for SHIELD, Coulson's crew will beat HYDRA to the prize. Unfortunately, someone from the underground agency will have to make the ultimate sacrifice to truly decode the secrets imbedded in the GH325.

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Even so, the life-saving serum may still have another task for its recipients.

"One of the really cool sci-fi elements of this show is that whatever this is, it seems to have been around for a while, and once it gets into your system, it starts to influence your behavior," Gregg told Entertainment Weekly. "I don't know that having solved the carving element of it or figuring out the city part of it is going to completely mean that that alien tissue is done with him."

Find out more when Agents of SHIELD airs Tuesdays at 9 p.m. ET on ABC. Click the video below to see a preview for the series' next episode, "The Things We Bury."

Tags: Marvel's Agents of S.H.I.E.L.D. television ABC Marvel