The story of Tasiyan begins where fate intertwines the lives of two individuals from different worlds. Shirin, the daughter of a wealthy and beloved factory owner, owes everything to her patriotic father. She's on the verge of an arranged marriage to her father's close friend's son, a union that promised a smooth and unburdened life.
But in another corner of the city, destiny has charted a different course for Amirdari. Amir, a free-spirited young man working in a small printing house, has been cast out by his religious father. In the fervent era of the revolution, where some were devout and others embraced communism, Amir's father, due to his religious convictions and his son's love for freedom, books, and wine, had banished him from home.
One day, Shirin steps into Amir's printing house to have something printed. Their eyes meet, sparking an immediate connection, and Amir falls madly in love with Shirin. The very next night, Amir's brother, also a devout man like their father, earnestly pleads with Amir to print some leaflets for him. These leaflets are destined for the university, a hotbed of student activism, to be distributed under the cover of night.
By ill fortune, on that same night, government agents raid the university and apprehend Amir along with the leaflets. But just as Amir is being interrogated, a more complex story unfolds. Amir's old friend, Nima, disguised as a SAVAK agent, sees him. Nima, with his influential words and vouching for Amir's innocence, secures his release from the interrogators.
Now, Amir learns of Shirin's wealthy suitor; a man from an influential family connected to the General. This burgeoning love, bordering on madness, compels Amir to make a desperate decision: to win Shirin and prove his standing, he joins SAVAK. It's a dangerous military profession, widely reviled at the time, and Amir knows his parents must never discover his true occupation.