The coup was mainly organised by Ion Iliescu,who was a member of PCR(The Communist Party of Romania) at the time and would become the first president of Romania,between 1990-1996 and 2000-2004,general Nicolae Militaru(if I'm allowed to make a joke,his name is literally Soldier,general Nicolae Soldier xd) and later general Ion Ioniţă who was a friend of Militaru.

In 1973,Ioniţă,minister of defence,had a fight with Ceauşescu and,Militaru,witnessing it,befriended with him.According to Militaru,in 1974,in a forest near Băneasa,Maurer he mets with Ioniţă and tells him that they have to do something about the current state of affairs(i.e. overthrow Ceauşescu).Militaru tried to connect the group of generals supporting Ioniţă with Iliescu's civilian group then.

In 1983,the first attempt fails.A year later,informed by Ioan Ursu about the details of Ceauşescu's visit to East Germany,the conspirators plan another coup d'etat,this time with the support of the Iliescu's civilian group.However,Ceauşescu found out about this,the plotters being betrayed by 2 of their generals.He orders several generals and divisions suspected of being part of the plot out of Bucharest in a single night.The plot disolved.Vasile Patilineț,an important member of the plot,died in an apparent "car accident"(i.e. most likely assasinated by the Securitate) in Turkey in 1986.Ion Ioniţă died of cancer in 1987,though there is some controversy on that,given that he died in 3 months.

The plotters wanted to imprison Nicolae Ceaşescu,Emil Bobu,Ilie Ceauşescu,Ion Dincă,Tudor Postelnicu and Ion Coman,all close people to Ceauşescu.After that,they would seize the radio and TV stations to announce the changes to the general populace.

Sources:

Ioan Scurtu - Revoluția Română din decembrie 1989 în context internațional (Ed. Enciclopedică/Ed. Institutului Revoluției Române din Decembrie 1989, București, 2006), chapter I, part 4. Situația României

^^^this is also my first answer pls tell me if there's something wrong