Ben and Joey . Good friends, common project about a movie, total trust one in other.
And the suspicions of Ben about plans of his friend, about his real identity and, not last, about the nature of an injection very suspect.
So, a form of childish - radical revenge. In elevator a presumed clue about his wrong impression but too late works, always , more than precise.
Good story, inspired performances and pretty moral. And, sure, a fist of cliches used not so bad .
In essence, one of stories working well especially for realism dose. And for honest image of loneliness, drops of paranoia and deep vulnerability.