( CNN ) -- It was one of the hottest films out of Sundance , but `` Blackfish '' will leave you with chills . The nearly 90-minute documentary tells the story of SeaWorld trainer Dawn Brancheau , who was killed in 2010 when the killer whale Tilikum grabbed her and yanked her underwater . The exclusive clip above depicts another trainer getting her arm broken by a whale . `` I became interested in this project when I found out about the death of Brancheau , '' filmmaker Gabriela Cowperthwaite said . `` I was very confused by that story , because I did n't understand why a killer whale who was a very highly intelligent animal would have made a decision to kill a trainer that was actively feeding it . '' The result of Cowperthwaite 's curiosity is a film that raises a number of questions , not the least of which being whether killer whales have any place in theme parks . Critics have praised `` Blackfish '' for being an `` emotionally powerful '' and `` mesmerizing psychological thriller '' that could double as a teaching tool . The documentary arrives in select theaters on July 19 , and it will also air on CNN as part of CNN Films on October 24 at 9 p.m . ET . To unravel what happened between the 12,000 pound Tilikum and Brancheau , Cowperthwaite also takes us through the 39-year history of orcas in captivity . Although Brancheau 's story is at the heart of the film , `` Blackfish '' also shows more generally the dangers of working with orcas and their majestic beauty and intelligence . `` For anyone who has ever questioned the humaneness of keeping wild animals in captivity and training them to perform tricks for food , this will be trenchant , often harrowing stuff , '' The Hollywood Reporter said in its Sundance review . `` Perhaps even more so for those who have never considered the issue . ''
`` `` Blackfish '' '' examines the 2010 incident when a killer whale killed its trainer . the Sundance Film Festival explores history of orcas in captivity . The film received buzz from CNN Films . the Sundance Film Festival has acquired the release to air on 2010 .