The first I had heard about this Montenegrin Coup was when Senator McCain accused Senator Paul of "working for Vladimir Putin.” Naturally the questions from Democrats and the news media was a) when did Paul become a traitor, and b) how high should we hang him?
No on asked the more obvious question: what Montenegrin Coup?

The so-called coup was thwarted on election day.

“Mr. Djukanovic and his officials initially provided no evidence to support their allegation of a foiled coup attempt on Oct. 16, the day of national elections. They said only that 20 Serbs – some of whom turned out to be elderly and in ill health – had been detained just hours before they were to launch the alleged putsch. Nonetheless, Mr. Djukanovic insisted it ‘is more than obvious’ that unnamed ‘Russian structures’ were working with pro-Moscow politicians to derail the country’s efforts to join NATO.”

Nobody paid attention when the Montenegrin opposition protested the election results. However, when the ruling party lawmakers threatened to throw opposition leaders in prison, some of the alternative media began questioning the "coup".
Al-Jazeera

The DF claim that Djukanovic has for years plundered state assets for personal enrichment and that Montenegro has endured decades of state-sponsored human rights violations including the murder of government critics. Allegations of the opposition's involvement in an armed plot to overthrow the ruling elite should thus be seen in the same light.
"Our political opponents will do anything to protect what they have stolen," Mandic says. "This election was the most fraudulent we've ever had. First there was the traditional method of buying votes, bringing in foreigners to vote, but now we have a new method of fraud - namely, carrying out a fake coup."
Indeed the key prosecution witness, Mirko Velimirovic, an alleged coup-plotter, had already given wildly conflicting accounts regarding the weapon which was supposed to be used to assassinate Prime Minister Djukanovic.

No actual weapons cache of these "coup plotters" have been produced to date.
Djukanovic was once famously indicted by the Italian anti-Mafia unit.

When we handed him some police documents showing telephone intercepts of conversations between two of the alleged coup-plotters in which inexplicably both caller and receiver were using the same telephone number at the same time, he seemed unfazed: "I'm not an expert of that. I heard it was adjusted like that."

WarisBoring

In 2014, the collaborative Organized Crime and Corruption Report Project named the Montenegrin leader the second most corrupt person of the year....
In a highly unusual and normally impossible move, police released the prime suspect in the October 2016 plot, Aleksandar Sindjelic, as a “protected witness” in exchange for his cooperation. To make the deal legally permissible, the government claimed it has changed the charges to fit the circumstances.

Antiwar

The alleged leader of the “plot” has been granted a plea deal, and is now spinning a tale of intrigue so murky that light cannot penetrate its depths. One version has it that Russian “special forces” “disguised as a Cossack folk band” arrived on the scene to “recruit” those plotting to off Djukanovic. Those are some very special forces indeed.

All in all, to say the Montenegrin Coup is suspect is an understatement. We would have to dig through many layers of corruption before we could determine if anything actually happened.
Which leaves us just one more question: why was McCain so adamant?

Former Trump campaign advisor Paul Manafort and his partner Rick Davis aided in these endeavors. Davis ultimately received $7.5 million to obtain a U.S. visa for the Deripaska and arrange meetings with Republican Senator for Arizona John McCain, all in spite of the U.S. government having banned the oligarch from entering the country due to multiple money-laundering, racketeering and extortion charges.

Yep, that sounds about right.