'Agents of SHIELD' Season 2 Episode 9 Spoilers: A Quote From Dante As All Hell Breaks Loose

There's a deathlessly famous quotation from the classic Italian poet Dante Aligheiri -- "Abandon all hope, ye who enter here."

It's a line from "Inferno," the epic poem about hell that was written by Dante, as the first part of his masterpiece, "The Divine Comedy."

That line has been used in so many novels, short stories, and even movies. On Tuesday, Dec. 2 from 9 p.m.-10 p.m., ET, it will be the turn of CBS' "Agents of S.H.I.E.L.D." to deal with horrors best left alone.

Season 2's Episode 9 is titled "...Ye Who Enter Here" and it tells of how S.H.I.E.L.D. discovers a city that existed before Hydra. It is an ancient city with ancient secrets and ancient terrors that have no place in the modern world.

The need to keep dangerous secrets preserved is most probably why making the highest kind of sacrifice is seen as the only effective way to learn the truth about the buried secrets.

Paul Zbyszewski wrote the teleplay for "...Ye Who Enter Here," with direction coming from Billy Gierhart.

"Agents of S.H.I.E.L.D." more properly known as "Marvel's Agents of S.H.I.E.L.D." (for Strategic Homeland Intervention, Enforcement and Logistics Division) has actors Clark Gregg playing the role of Agent Phil Coulson, Ming-Na Wen as Agent Melinda May, Brett Dalton as Grant Ward, Chloe Bennet as Skye, Iain De Caestecker as Agent Leo Fitz, Elizabeth Henstridge as Agent Jemma Simmons and Nick Blood as Lance Hunter.

The guest actors for "...Ye Who Enter Here" include B.J. Britt as Triplett, Adrianne Palicki as Bobbi Morse, Henry Simmons as Alphonso "Mack" Mackenzie, Ruth Negga as Raina, Patton Oswalt as Sam/Billy Koenig, Reed Diamond as Daniel Whitehall, Jeffrey Corbett as Chad, and Brittnee Garza as Cashier.