In Russia during the Napoleonic Wars, Boris Grushenko is a neurotic and cowardly intellectual with an unrequited love for his beautiful cousin Sonja. Despite his pacifist inclinations, Boris reluctantly joins the Russian army when Napoleon invades. Against all odds, he inadvertently becomes a war hero, though he remains more focused on philosophical musings and avoiding danger. After a series of absurd mishaps and false heroics, Boris survives the war and returns home. When he learns that Sonja is unhappily married, he sees an opportunity to finally win her love. Through a series of comedic schemes, he eventually convinces her to marry him, but their union is anything but blissful as they continually debate existential topics.

Boris and Sonja concoct a plan to assassinate Napoleon in a bid to end the tyranny and achieve greatness. They travel across Europe in a series of comically inept attempts to carry out their plot. Along the way, they encounter odd characters and face various moral dilemmas, leading to deep but humorous discussions about life, death, and love. Their journey is filled with unexpected twists and turns, testing their wits and relationship at every step. In a crescendo of philosophical and farcical elements, the couple's plan reaches a turning point, revealing much about their characters and the nature of human folly.