In the ramp up to its season finale, everyone is wondering how Marvel's ABC drama "Agents of S.H.I.E.L.D." will tie into "Captain America: Civil War." But with the latest episode synopsis, the spy series may be drawing on some other elements of the Marvel Cinematic Universe by drawing in a few comic-influenced characters previously unseen on screen.

Today Marvel released the following synopsis for May 3's "Failed Experiments" episode:

THE INHUMAN WAR ESCALATES, ON "MARVEL'S AGENTS OF S.H.I.E.L.D." ON ABC

"Failed Experiments" - Coulson and his team race to combat Hive's control over the Inhumans, as their enemy's deadly plan for the human race is revealed, on "Marvel's Agents of S.H.I.E.L.D.," TUESDAY, MAY 3 (9:00-10:00 p.m. EDT), on the ABC Television Network.

"Marvel's Agents of S.H.I.E.L.D." stars Clark Gregg as Director Phil Coulson, Ming-Na Wen as Agent Melinda May, Brett Dalton as Grant Ward, Chloe Bennet as Agent Daisy Johnson, Iain De Caestecker as Agent Leo Fitz, Elizabeth Henstridge as Agent Jemma Simmons, Nick Blood as Agent Lance Hunter, Adrianne Palicki as Agent Bobbi Morse, Henry Simmons as Agent Alphonso "Mack" MacKenzie and Luke Mitchell as Lincoln Campbell.

Guest starring are Axle Whitehead as James, John Hannah as Holden Radcliffe, Alicia Vela-Bailey as Alisha, Alexander Wraith as Agent Anderson, Mark Atteberry as Kirk Vogel, Derek Phillips as Agent O'Brien, Briana Venskus as Agent Piper, Lynn Longosz as Kree reaper #1 and Chris Hubbard as Kree reaper #2.

"Failed Experiments" was written by Brent Fletcher and directed by Wendey Stanzler.

Of course, the inclusion of something called "Kree Reapers" holds promise both for the show's Inhumans storyline and for fans wondering what's up with the cosmic empire since "Guardians of the Galaxy." Meanwhile, the character Holden Radcliffe is a villain from Marvel's early '00s series "Machine Teen" -a reimagining of Machine Man. Whether this Radcliffe will play a part in Hydra's inner circle or something else is yet to be seen.