For two years she lived and worked in an isolated house on a farm in which there was a printing press for the publication, O Militante, a magazine for PCP members, together with other communist party propaganda materials.

In this house, on 25 March 1949, she, Cunhal, and Militão Ribeiro were arrested by the PIDE, the Estado Novo's secret police.

Refusing to make any statements or sign records of the interrogations, she was then held in complete isolation for six months, with visits only allowed every 15 days and for just 15 minutes.

In 1957, although she did not participate in person at the illegal 5th Congress of the PCP, she was elected as an alternate member of the Central Committee of the Portuguese Communist Party.

She eventually ended up being held in the Caxias prison near Lisbon for 9 years and three months, regularly being punished for any small infraction.

In November, she married António Santo, who was released at the same time, and, shortly after, they left in secret for the Soviet Union, where they spent 18 months trying to recover from the prison experience.