Asha Rangappa is a senior lecturer at Yale's Jackson Institute for Global Affairs. She is a former special agent in the FBI, specializing in counterintelligence investigations. Follow her @AshaRangappa_ . The views expressed in this commentary are her own. View more opinion at CNN.

(CNN) The twists, turns and characters outlined in the complaint filed by an unnamed whistleblower to the intelligence community's inspector general read like a pilot for a new television series. This however is real life and, with impeachment investigations beginning, understanding the key elements of the complaint will be critical in following the events that unfold.

While the White House continues to deny any wrongdoing, the scope of activity presented in the complaint raises many alarming issues. Here are the five main plot points to watch for as Congress takes steps to follow up on these blockbuster allegations.

1) The complaint has been corroborated

A common talking point among many supporters of President Donald Trump is that the complaint is based on second-hand information , or hearsay. And, yes, the whistleblower does note not being "a direct witness to most of the events described." But this point would have been taken into consideration when the ICIG reviewed whether the complaint was "credible," as he was required to do under the whistleblower statute . Notably, the ICIG still concluded that the report was "credible."

This judgment could be questioned if it weren't for two important things. First, the day before the release of the whistleblower's complaint, the White House released a memo containing a real-time transcription of Trump's call with Ukrainian President Volodymyr Zelensky. This call is the same one referenced in Part I of the complaint. Even based on secondhand knowledge, the whistleblower's account of the call was identical in key details to what actually took place: That the President requested Ukraine to 1) investigate the activities of Vice President Joe Biden and his son, Hunter Biden; 2) assist in efforts to link 2016 election interference with Ukraine; and 3) work with Attorney General Bill Barr and Trump's personal attorney, Rudy Giuliani, on these matters.

More importantly, the complaint indicates that it is based on accounts from at least six White House officials who did have consistent, first-hand knowledge of the call and other events described in the complaint. This means that there are at least a half dozen witnesses whom Congress can call to corroborate the allegations made in the complaint.

2) There appears to have been a coverup

No scandal is truly complete without a coverup, and this one appears to have it. Part II of the whistleblower's complaint alleges that the officials who witnessed the call first hand were directed by White House lawyers to move the verbatim transcript from where it would normally be stored to a separate system which is used for highly classified information and to which access is highly restricted. (This part of the complaint has been confirmed by the White House.) Because the President's call with Ukraine did not relate to a "codeword" operation (typically used for covert actions), it would ordinarily not meet the standards to be stored on the restricted server. The classification markings on the released transcript supports this, as it is marked at the Secret classification level, a relatively low level of classification (while not the lowest).

Importantly, the complaint indicates that officials who received the orders believed that the transcript was moved in order to conceal evidence that might be politically embarrassing to the President and the White House -- and the appendix to the complaint alleges that the systems had been misused on other occasions for the same purpose.

In addition to an attempt to conceal a possible crime or abuse of power by the President, this on its own could be a violation of an Executive Order , which prohibits "overclassifying" information in order to "prevent embarrassment to a person, organization, or agency." Congress will undoubtedly seek to find out who gave orders to try to conceal these transcripts from further distribution and possibly seek to obtain other "hidden" transcripts with world leaders.

3) The State Department may have facilitated Trump's activities

The complaint indicates that at least one State Department official, T. Ulrich Brechbuhl, listened in on the call between Trump and Zelensky (though the State Department has denied this to be true). In addition, Part III of the complaint states that US Special Representative for Ukraine Negotiations Kurt Volker (who has since resigned), along with US Ambassador to the EU, Gordon Sondland, met with Zelensky and other Ukrainian officials on the day following Trump's call. The whistleblower received multiple readouts of these meetings, which indicated that these State Department officials advised Ukrainian officials on how to "navigate" the requests that Trump made to Zelensky on the phone.

If true, this would mean that officials from the State Department were not only aware of Trump (ab)using the power of his office to extract personal favors from a foreign nation, but were engaged in efforts to help bring them to fruition. The process of organizing these official meetings, as well as the readouts of what took place in them, would leave an extensive paper trail.

Three committees of Congress have already subpoenaed Secretary of State Mike Pompeo to produce all documents related to meetings with Ukraine, and Pompeo himself will likely be called to testify about them. If he complies, the public will learn more about what expectations were conveyed to Zelensky regarding his compliance with Trump's wishes. If he doesn't comply, the House can use his defiance as evidence of obstruction, which could form its own basis for an article of impeachment.

4) The Department of Justice may have ignored a clear conflict of interest

The whistleblower complaint contains only a few references to Barr -- that he was "involved" in Trump's request to Ukraine to investigate his political opponent, and that he was mentioned "in tandem" with Trump's personal lawyer, Rudy Giuliani, several times (more on Giuliani, below). The primary source -- the White House memo -- substantiates this allegation, with Trump telling Zelensky to communicate with Barr on the investigations he requested. Notably, the Justice Department released a statement just after the White House transcript release went public, denying Barr made contact with the Ukrainians.

But Barr's role in this unfolding drama takes on significance after the complaint was filed. This is because once the ICIG determined that the complaint was credible, he passed the complaint on to Acting Director of National Intelligence Joseph Maguire. At that point, Maguire was required by law to transmit the complaint, along with any additional comments he chose to provide, to Congress.

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He didn't. Instead, Maguire took the complaint to the White House, ostensibly (based on his testimony to Congress) to inquire whether the contents were covered by executive privilege. Two things happened next. First, the White House obtained a legal opinion from the Office of Legal Counsel in the Department of Justice, which determined that the subject matter of the complaint did not fall under the jurisdiction of the DNI, and therefore could not be brought under the whistleblower statute.

The OLC stated that the proper channel for the DNI was to present a criminal referral of the matter to the Justice Department. The DNI did so, and the Justice Department determined that the complaint required no further investigation, either as a possible violation of campaign finance laws (which prohibits soliciting any "thing of value" from a foreign state or person) or any other law.

Of course, Barr is ultimately in charge of both the OLC and the Criminal Division of the FBI. Since he himself is implicated in the allegations, he should have been required to recuse in any evaluation of the complaint by his agency.

Congress will likely seek to find out what role he played in either the OLC decision or the decision not to investigate, why Barr did not recuse and if he played any other role in the allegations laid out in the complaint. Congress may also choose to call the head of the OLC, Steven Engel, to explain his reasoning, and in particular why issues regarding handling of classified information would not fall under the jurisdiction of the DNI.

5) Rudy Giuliani, international man of mystery

Perhaps the most perplexing part of the whistleblower's complaint is the role of Rudy Giuliani, Trump's personal attorney. According to the complaint, Giuliani reached out privately to several advisers to the Ukrainian President as, based on accounts of US officials, "direct" follow-up to Trump's requests in his July 25 phone call. Notably, these meetings are substantiated by public statements Giuliani made on TV and in news interviews. In addition, footnote 9 of the complaint states that Giuliani claimed to be working on gathering information to provide to the Justice Department as part of its official investigation into to "origins" of the Russia probe, which is currently being handled by Connecticut US Attorney John Durham, and who is also reportedly looking into Ukraine's role in the 2016 election interference. (It should be noted here that the intelligence community has unanimously concluded that Russia was behind said interference.)

Congress will no doubt want to hear directly from Giuliani about his role in all of these efforts. Giuliani has already indicated that he may invoke attorney-client privilege to refrain from testifying (because he is acting in a private, rather than official capacity, executive privilege would not apply). But this may be an uphill battle.

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The crime-fraud exception states that the attorney-client privilege cannot be used as a shield for potentially illegal activity. The Supreme Court's decision in U.S. v. Nixon did not allow the President to use executive privilege to shield potentially illegal conduct in a criminal proceeding. This precedent would likely apply as strongly in the case of a private attorney-client privilege.

Even beyond that, the privilege only covers communications between Giuliani and Trump himself: Communications between Giuliani and officials either in the State Department or Justice Department would not be covered. Congress will want to find out: How closely was Giuliani working with US government officials who were aware that he was tasked with carrying out Trump's potentially illegal requests?

Given the sheer number of characters and plot lines emerging in the whistleblower saga, the American public may have a difficult time keeping up. But the only thing they have to remember is the most important question in any scandal: Who knew what, and when did they know it?

Note: This op-ed has been updated to correct the classification level of the rough transcript.