Short answers, pulled from the story.
The Tudeh Party of Iran emerged on the 29th of September 1941, born from a meeting at the residence of Soleiman Eskandari. A group known as the Group of the 53 members had just been released from prison following the British-Soviet Allied invasion that ended Reza Shah's reign.
By early 1945, the group had created the first mass organization in Iranian history with an estimated 2,200 hard-core members. Its main newspaper, Rahbar, achieved a circulation exceeding 100,000 copies which tripled the circulation of the semi-official Ettelaat daily.
In February 1949, an attempt was made on the life of Shah Mohammad Reza Pahlavi and the government blamed the party and banned it immediately. Security forces rounded up some 200 leaders and cadres during this crackdown while confiscating assets and dissolving affiliated organizations like the Central Council.
Mass arrests following the 1953 coup destroyed much of the Tudeh Party structure between 1953 and 1957 when security forces tracked down 4,121 party members using cryptographic codes likely provided by CIA know-how. The arrest and execution of Khosro Roozbeh in 1957 signaled the end of this process.
In February 1983, leaders of the Tudeh Party were arrested and the organization disbanded leaving Iran effectively as a one-party state with more than 10,000 members imprisoned. From May 1983 to May 1984 almost all leadership appeared on television confessing to treason and subversion under torture as reported by General Secretary Noureddin Kianouri.