A man named Mr. M took a train to Helsinki, the contemporary Finnish capital in the middle of the night. He spent the night in a park, but was robbed by three gangsters and brutally beaten. He died after being sent to the hospital, but was resurrected inexplicably. He walked out of the hospital and strolled into the slums of this city. Here, he was treated kindly by Caesar and her husband Nieminen. Guard Antila helped him find an industrial container right for shelter. At this time, M has completely lost his memory, not only forgot his past, but also his current identity. He could not find a job, but was eventually hired by a Finnish charity "Christian Salvation Army". M was attracted by Irma, a female staff member of the agency, and fell in love accidentally. M himself was originally a rock fan. Now he manages the band of the "Christian Salvation Army", helping to introduce more lively contemporary music. They held several open-air concerts with great success and great fame. M and Irma become a couple. In the dock, when M saw a man cutting metal with an acetylene blowpipe, his memory was suddenly aroused. His great skill prompted the foreman to assign him a job.
M needs to go to the bank to open a current account, but happened to encounter a man robbing the bank with a musket. M and a cashier were locked in the vault by the gangsters and were not rescued until the police arrived at the scene. Although M is not involved in the robbery, the police inspector intends to convict him of "vagrancy" and put him in jail. Fortunately, Irma sent a lawyer to rescue him. M accidentally encountered the person who had robbed the bank. He explained to M that he was not a robber and the cash he stole should actually belong to him, but he was confiscated by the bank after his company went bankrupt. He asked M to take responsibility and distribute the money to his employees as wages owed to them, and then shot himself. Now that the truth about the bank robbery has come to light, M's photo has also been published in the newspaper. Unexpectedly, the police inspector brought new news: A woman in the northern Finnish town of Murmes recognized M as her missing husband. M sadly bid farewell to Irma and embarked on a journey to the north. He finally found that the relationship between him and his wife was very tense, the two were on the verge of divorce, and she had a new lover. M willingly broke away from his wife and returned to Helsinki. He encountered those gangsters again, and was beaten up like the last time. This time, the gangsters were defeated by the people they had bullied. M and Irma are reunited again
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