Cassandra's Dream (2007) ending / spoiler
Ian and Terry manage to shoot Martin Burns as he's leaving his mother's house, with their Zip Guns. Terry can't deal with the guilt and wants to turn himself in. Howard orders Ian to deal with his brother. While on their boat, Ian goes to overdose his brother but can't bring himself to do it. A fight breaks out between them, resulting in Ian being knocked down some stairs where he breaks his neck. Overcome with grief by what he's just done, Terry jumps over board and lets himself drown.
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