简介：In1931,Britain'smostadvancedsubmarinecollidedwithacargoshipoffthecoastofChinaandsank.Threehourslater,sixsailorssurfaced,barelyconscious.Theywerethefirstmenevertoescapefromasunkensubmarineusingaproto-scubadevice.Theirstoryhitheadlinesandwentontoinspireafeaturefilm.Themiraculousescapechangedmarinesafetyforever.Buttheirnames,andtheirsubmarine,graduallysankintoobscurity.Beijing-basedjournalistandscubainstructorStevenSchwankertwaslookingfornearbywreckstodivewhenhefoundHMSPoseidononalistofunexploredsites.Hisfive-yearsearchforthesubmarinebecameaprivateobsessionthatwouldchallengeofficialaccountsoftheescape,andrevealasecrethistory.…