Mr. Reliable tells the true story of Wally Mellish, an ex-convict in 1960s Australia. Just released from prison, all he wants to do is live a quiet life with his girlfriend Beryl. A misunderstanding, quickly gets out of control, when two police officers pay him a visit, resulting in Wally, Beryl and her child being trapped in their house. Surrounded by armed police, the community is under the impression that Wally is holding everyone hostage. Events quickly spiral into a media circus as, through the siege, Wally - inadvertently - manages to become a symbol for the anti-war movement.