( CNN ) -- Another gruesome video . Another beheading of a Western captive by ISIS . And another family warned that its loved one may be next . For Alan Henning 's family , the nightmare has turned into reality . Now Abdul-Rahman Kassig 's family is hoping for a miracle . Both Henning and Kassig risked their lives to help strangers besieged by the Syrian civil war . Over the weekend , hundreds of people attended a service in Manchester , England , to remember Henning . And Sunday night , Kassig 's parents issued another plea for their son . Here are the stories of the aid workers snatched by militants bent on using them as political pawns : . Henning : A 'national hero ' Not even the calls of 200 mosques in Britain were enough to stop radical militants from decapitating Henning , a 47-year-old taxi driver from near Manchester . `` Alan Henning was our local and national hero , '' a joint statement from the mosques said . `` We will remember him as a tireless and selfless volunteer aid worker whose only concern was to help people in need . '' The mosques also slammed the terror group who took him . `` The killing of Alan Henning was a cowardly and criminal act of appalling brutality by a group who do not represent Islam at all and in fact are an insult to the Islamic faith , '' their statement said . Henning joined a group of volunteers who traveled to Syria in December 2013 to deliver food , water and medical supplies to people afflicted by the country 's devastating civil war . He was abducted by masked gunmen the day after Christmas , other people in the aid convoy said . His wife , Barbara , pleaded for her husband 's release , but to no avail . ISIS released the video of Henning 's decapitation on Friday . It said the killing was a response to the UK joining the U.S.-led bombing campaign against the group in Iraq and Syria . Some of Henning 's fellow aid workers believe the British Parliament 's decision to authorize bombing ISIS in Iraq may have triggered their friend 's slaughter . `` By joining the U.S. airstrikes , we handed Alan , and many other Western hostages , a death sentence , '' aid worker Dr. Shameela Islam-Zulfiqar said . But British Prime Minister David Cameron said the `` abhorrent '' killing of Henning means allies must continue trying to `` do everything we can to defeat this organization . '' And as it did in the beheading videos of American freelance journalists James Foley and Steven Sotloff and British aid worker David Haines , ISIS threatened to decapitate another Westerner . It showed American aid worker Abdul-Rahman Kassig and said he would be next . ISIS video similar to others , does n't run as long . Kassig : ' I am an idealist '
Ed and Paula Kassig plead for ISIS to release their son . Abdul-Rahman Kassig served as a U.S. Army Ranger and went to Syria as an aid worker . He was captured by the Islamic State in August 2014, along with his wife and two children. Henning was a `` local and national hero , '' a joint statement from 200 mosques says .