London. British spy, Ian Munro, is briefed by his boss Naylor about the suspicious deaths of people and animals in Lahti, Finland – the possible result of a toxic gas. Munro travels to Finland to investigate. There, a local contact, Pentti Virolainen, is shot dead while Munro looks on, unable to intervene. Munro calls London for further orders. Meanwhile, he
reads an article about Finnish businessman Jorma Lappalainen, owner of a bioengineering business.That evening, Munro meets the lovely Riitta Koivisto, who seems rather too curious about him. At midnight, Koivisto visits him in his hotel room, and they spend the night together. However, when Munro wakes up, he realises he has been drugged and discovers his room has been searched.The next day, Munro is given an address to visit. Before doing so, he realises he is being followed. Munro plays for time, and calls London for help. Still trying to
evade his pursuers, Munro returns to the hotel, where he escapes detection by pretending to be the drinking partner of a hotel guest sleeping off a binge. Munro remains in the safety of the guest’s room until he receives a message from London, which is a car number.Disguised in the hotel guest’s clothes, Munro first deals with the henchman guarding the rear of the hotel. Leaving him unconscious, he rushes to the front where he alerts the other henchmen to a fight in progress at the rear. Munro escapes in the car parked outside.In the suburbs of Lahti, he meets Sirpa Virolainen, sister of the murdered Pentti Virolainen. She tells Munro that Pentti worked for a bioengineeringcompany called Bioratkaisut, the same company that Koivisto worked for. Pentti discovered the company was developing poison gas, and spoke about this to
a British scientist, an action which cost him his life. Sirpa gives Munro a piece of paper left by Pentti, probably a chemical formula.Munro realises he must take Sirpa to a place of safety, and drives her to Helsinki. On the way he sees two jeeps following. He manages to shake off one jeep, but the other forces Munro’s car off the road. When Munro and Sirpa regain consciousness, they are held captive by Jorma Lappalainen, who admits that his companies are developing poison gas for a foreign power. Lappalainen locks them in a sauna, and turns up the temperature to a lethal level. Munro and Sirpa manage to escape, butare intercepted by Lappalainen. Sirpa is shot but Munro eventually disarms Lappalainen. Rather than face justice, Lappalainen commits suicide by drinking poison.Fortunately, Sirpa has only been slightly wounded. After giving evidence to the authorities and learning that Koivisto is Lappalainen’s sister, Munro takes Sirpa home. The next day, when about to leave for London, Munro receives a call from Koivisto, who is holding Sirpa hostage at the top of a ski jump.Munro arrives to find Sirpa apparently dead, and Koivisto threatening him with a gun. He realises his only chance is to keep her talking. A groan from Sirpa distracts Koivisto and Munro seizes his chance to disarm her. A fight ensues, ending with a lethal blow to Koivisto’s neck. Munro is able to save Sirpa’s life. The case is over.