The Olsen Gang’s Last Trick

After 17 years, Egon is placed at the Institute for Theoretical Crime. He is allowed a brief stint outside for a televised talk show, which rekindles attention on him. Benny and Kjeld watch the broadcast and decide to seek him out, setting the plot in motion.

Just after the broadcast, Egon leaves the studio to seek a toilet, where he runs into Benny outside. The chance reunion leads them to unanimously decide to visit Kjeld at the nursing home. Their meeting reopens old ties and hints at a new scheme.

Kjeld, living in a nursing home after Yvonne’s death, meets Ruth, a woman he hopes to buy an apartment in Málaga with. The encounter adds a personal thread to the gang's tale and foreshadows Ruth's role in the plan. The three characters—Kjeld, Ruth, and the gang—start to become entangled.

Egon returns to his long-held ambition: to lead the Olsen gang to a large capital by stealing the English crown jewels. He reflects that during his years in psychiatry he drafted numerous plans, many confiscated by the superintendent, and now he seeks to recover them from the safe. The plan is to exploit the safety net to break out.

The broadcast also alerts Hallandsen, the department head at the Ministry of Justice, who sees Egon’s reappearance as a threat to state secrets. He assigns Holm-Hansen to locate Egon and retrieve the Wandenberg documents before they cause a catastrophe.

Holm-Hansen consults retired detective Jensen, who had waited 17 years due to a computer error. Jensen advises checking the Franz Jäger safe from 1944, the only one left in Denmark, located in the Department of Theoretical Crime.

As Egon plans the theft, the headmaster confronts him and attempts to confine him again. Holm-Hansen arrives at the last moment to intervene, allowing Egon to leave with Kjeld and Benny.

Egon is brought to Hallandsen, who assigns him to steal the Wandenberg documents, promising a reward. Two ministry officers assist, and the theft from the Ministry of Foreign Affairs' archive happens within minutes.

After Hallandsen has obtained the documents, Egon demands the promised reward but is instead imprisoned in a dungeon. Kjeld and Benny manage to free him at the last moment, avoiding another setback in their caper.

Hallandsen plans to destroy the suitcase with the Wandenberg documents; Egon intends to prevent this and uses the documents to leverage the minister. With Benny and Kjeld, they retrieve the suitcase using improvised tools, and Hallandsen is deeply shocked as he drives away.

The Olsen gang drives toward the construction site of the Øresund connection to deliver the suitcase when Ruth unexpectedly joins in Kjeld's place, claiming he is unwell. Egon reluctantly accepts her presence as part of the plan.

At the construction site, Bøffen and Alf attack again and push the group into a construction cave. They fight back, and Egon’s leadership helps them escape with the Wandenberg documents and his plans intact.

Kjeld's son Børge, now an international company manager, arrives in Denmark after learning what has happened. He seeks out Egon, Benny, and Ruth and finally locates the assembled gang at the construction site.

Benny says goodbye as Egon confronts the loss of his plans when Ruth and Alf throw the suitcase containing the plans and the Wandenberg documents onto a construction machine. Egon watches in disbelief as the vital documents disappear, while Hallandsen contemplates retreat.

Egon, along with Benny, Kjeld, Ruth, and Alf, travels to Børge's villa in Portugal to live out the rest of their days in peace. Yet Egon still harbors the lingering plan to steal the English crown jewels, ensuring the dream outlives the day’s events.