It's a Mad, Mad, Mad, Mad World

Smiler Grogan, a freshly released convict, reveals the $350,000 treasure location as his dying act. He shares this information with nearby motorists while taking his final breaths, setting the entire chaotic treasure hunt in motion. His motive appears to be either a final act of spite toward the crooked businessman who originally buried the money, or simply a dying man's impulse to unload a dramatic secret.

After Grogan reveals the money's location, the group of motorists argue about how to divide the $350,000 but cannot reach a fair agreement. Tensions escalate quickly, and rather than wait to work out a distribution plan, each person decides to race to Santa Rosita State Park to claim the treasure for themselves. This inability to cooperate despite shared knowledge sets up the film's central premise.

The treasure hunters spend the entire movie searching for a 'big W' to dig beneath, believing it to be a prominent landmark. However, when they finally reach Santa Rosita State Park, they discover the 'big W' is actually a cluster of four palm trees arranged in a W shape. The treasure is buried beneath this unexpected marker, making the entire frantic chase turn on a simple visual misunderstanding.

Grogan's vague description of 'a big W' sets up the entire misunderstanding that drives the plot.

Otto Meyer gives Lennie Pike a ride after hearing about the hidden money. However, once Meyer learns the specifics of the treasure location, greed takes over and he decides to pursue it independently. He tricks Pike into being detained by service station attendants, then abandons him to race to Santa Rosita alone. Meyer's betrayal demonstrates how the promise of money corrupts even brief alliances.

Captain Culpeper, Santa Rosita's police chief, initially appears motivated to catch the treasure hunters to close the Grogan case before retirement. However, after suffering a mental breakdown due to family tensions and learning his pension is minuscule, Culpeper decides to keep the money for himself. He poses as an officer offering leniency but secretly intends to abscond with the entire $350,000, viewing it as his only chance for financial security.

Culpeper's frustration with his small pension and family problems hint at his moral descent.

Melville Crump and his wife Monica charter a rickety biplane to reach Santa Rosita quickly. Upon landing near a hardware store, they enter the building but find themselves locked in the basement, either by accident or because they were trapped inside while searching for an exit. They must use dynamite to blast their way out, which delays their treasure hunt significantly.

Ding Bell and Benjy Benjamin charter a small airplane to reach Las Vegas, but their pilot is intoxicated. During the flight, the inebriated pilot passes out from alcohol, forcing Ding and Benjy to take control of the aircraft themselves. They manage a perilous landing on solid ground before hiring a cab to continue their journey to the treasure.

After J. Russell Finch crashes into Lennie Pike's furniture truck, he convinces Colonel J. Algernon Hawthorne to drive the group to Santa Rosita. During the journey, a heated argument erupts between Finch and Hawthorne. Fed up with the conflict, Mrs. Marcus and Emmeline abandon both men and hitch a ride separately, determined to reach the treasure through their own means.

Captain Culpeper is desperate to resolve the Grogan case before his retirement. While monitoring the treasure hunters, he receives devastating personal news: his family tensions have reached a breaking point and his pension is far smaller than he expected. These mounting pressures combine to trigger a complete mental breakdown at the police station, leaving him unable to function.

Culpeper's frustration with his inadequate pension and family problems plant the seeds for his breakdown.

After the treasure is uncovered, Culpeper's attempt to steal the money triggers a chaotic chase through an abandoned building. The motorists pursue him onto a rickety fire escape. As they scramble for the scattered cash, the combined weight and frantic movement causes the fire department rescue ladder to spin violently, throwing all parties off and resulting in catastrophic injuries to everyone involved.

In the final scene, Mrs. Marcus storms into the prison hospital to scold the men, but she slips on a banana peel and crashes to the floor. Despite their severe injuries and lost fortune, the men burst into laughter at this absurd moment. Even Culpeper joins in, unable to resist the comedy. This unexpected shared laughter represents a moment of camaraderie and acceptance of their shared fate, turning their bitter situation into dark comedy.

Each group uses a different mode of transportation to reach the treasure. Melville and Monica charter a biplane but get trapped in a hardware store. Ding and Benjy take a small plane whose pilot passes out. J. Russell Finch crashes into a truck and convinces Colonel Hawthorne to drive. Otto Meyer steals multiple cars after losing one to a river. Lennie Pike steals a tow truck. Eventually, all fourteen adventurers converge on Santa Rosita through various chaotic means.

Otto Meyer stops to help a stranded miner reach his remote cabin. On the return trip to the highway, Meyer attempts to cross a deep river but misjudges the current. His car gets swept away by the water, forcing him to steal another motorist's vehicle to continue his pursuit of the treasure. This setback demonstrates the escalating consequences of his greed.