Short answers, pulled from the story.
King Michael I led the 1944 Romanian coup d'état by ordering weapons against Nazi forces and arresting Prime Minister Ion Antonescu. Communist conspirators Emil Bodnăraș and Lucrețiu Pătrășcanu met with King Michael's representatives to plan the operation.
King Michael announced over radio at 10 pm on the 23rd of August 1944 that Antonescu had been deposed. The announcement declared acceptance of an armistice with Allied Powers and the Soviet Union.
Ion Antonescu was handed over to communists on the 1st of September before being returned to Romania for trial. He was executed in 1946 after a public proceeding.
Approximately 140,000 Romanian prisoners of war were taken during this period. About 130,000 were transported to the Soviet Union where many died in prison camps.
Albert Speer later described Romania's defection as decisive because it deprived Nazi Germany of critical oil resources. Hitler admitted for the first time that the war was lost due to this loss.