In an 18th-century European city under siege from the Ottoman Empire, a theatrical troupe is performing a play about the legendary Baron Munchausen's fantastical adventures. As the play unfolds, an elderly man claiming to be the real Baron interrupts, insisting that the portrayal is all wrong. To the astonishment of the audience, he begins recounting his incredible life story, offering an entirely different narrative filled with his preposterous exploits. The Baron's tales feature his supernatural companions: a man with superhuman speed, another with incredible strength, a sharpshooter with uncanny accuracy, and one with preternatural lung capacity. During his narrative, the city continues to endure the siege, with danger drawing ever closer. As his story weaves through the past and the present, the Baron's audaciousness captivates the crowd, offering a fleeting glimpse of hope amid despair.

Determined to prove his stories true and to save the beleaguered city, the Baron sets out on a quest to find his old friends. A young girl from the audience named Sally becomes swept up in the Baron's mission, joining him on his journey. Together, they embark through a landscape of myth and wonder, encountering monstrous sea creatures, the Grim Reaper, and the treachery of a sultan. Each encounter presents a test that draws upon the extraordinary abilities of his companions and the Baron's own unyielding spirit. As they venture beyond the confines of reality, their adventures challenge the distinction between myth and truth, blurring the lines of what is genuinely possible.