The Octopod is grabbed by a colossal squid. The Octonauts are unable to break free due to the hooks on the ends of the squid's tentacles. Fortunately the arrival of some sperm whales turns the squid from hunter to hunted.
为求仙药线索，一行人抵达统治岛屿的怪物"天仙"之居城。欲从岛屿生还，死囚与处刑人已不得不携手合作。与此同时，幕府以"山田浅卫门殊现"为首，下令增派人员登陆神仙乡。其中竟可见与画眉丸素有渊源的石隐众之身影。正当画眉丸等人欲尽快寻得仙药逃离孤岛之际，天仙们却拦住了他们的去路——围绕仙药的争夺，即将迎来"人类"与"天仙"的全面对决——！！
