Because of rising political tensions and a paranoid Russia Tsar, the port of Vladivostok is highly militarised. Passepartout and Fogg will be arrested under suspicion of being British spies if they try to stay overnight or explore. If arrested, they will spend four days in jail. However, this outcome can be avoided by acquiring military papers from the governor in Omsk. However, if Passepartout was associated with the riots in St Petersburg, they will be arrested regardless of having military papers in your possession.
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