The terror group ISIS released a new video on Friday in which they horrifically behead British aid worker Alan Henning, the fourth Westerner to have been murdered in recent weeks.

At the end of the video, ISIS threatens American captive Peter Kassig, with the very clear implication that if the U.S. and its allies continue a campaign of airstrikes against ISIS, Kassig will be the next to die.

Kassig's parents have released a desperate plea to ISIS, asking for them to spare their son's life.

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Leland Vittert joined Uma Pemmaraju on America's News Headquarters and explained that Kassig, an Indiana native and former Army Ranger, was inspired to become an aid worker in the Middle East during a trip to Beirut, Lebanon.

Kassig was captured by ISIS while helping Syrian refugees around the city of Raqqa in early October of last year, although his abduction was not publicly reported until now.

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Kassig's parents, Ed and Paula, have taken to YouTube to issue a desperate plea to ISIS for their son's safe return.

“We are so very proud of you and the work you have done to bring humanitarian aid to the Syrian people," Paula Kassig addressed to her son in the video.

"We implore those who are holding you to show mercy and use their power to let you go."

Watch the clip from America's News Headquarters above and see the Kassigs' full YouTube message below.

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