Robert Mueller’s investigation is now 1 year old. Watching the slow reveal of witnesses, search warrants and subpoenas, the president’s supporters and his opponents may despair that it will never come to an end.

But buckle your seat belts and grab the oxygen masks. It’s about to get interesting. From my vantage point as a former federal prosecutor, Senate Judiciary aide and White House lawyer, the special counsel’s path forward seems very clear—almost inevitable. With the caveat that the future is of course uncertain, here are three predictions for the dramatic weeks ahead:

Mueller will likely wrap up his investigation this summer. It is an ironclad principle that prosecutors should not take action that could influence an election. As George W. Bush’s attorney general, Michael Mukasey, told his prosecutors by written guidance in 2008, “Law enforcement officers and prosecutors may never select the timing of investigative steps or criminal charges for the purpose of affecting any election, or for the purpose of giving an advantage or disadvantage to any candidate or political party.” The Hatch Act, he continued, “prohibits us from using our authority for the purpose of affecting election results.”

Mukasey’s declaration was such a clear and obvious declaration of principle that four years later, President Barack Obama’s attorney general, Eric Holder, reissued it in virtually identical language. That guidance still stands.

Indeed, the bipartisan reaction among legal scholars and former officials to FBI Director James Comey’s public declaration in October 2016 that he was reopening the Hillary Clinton email investigation formed the bulk of Deputy Attorney General Rod Rosenstein’s justification for the Comey firing one year ago.

So Mueller must act fast to finish his investigation—or he must wait until after the November 2018 elections. And if he waits, he knows every action he takes in those months leading up to the election will be scrutinized for political effect. Surely, he does not want to have to explain in his memoirs how his actions unintentionally affected the election.

How fast must he move? When does the window for action close? Kenneth Starr did not issue his report recommending the impeachment of Bill Clinton until September 11, 1998, also a midterm election year. The timing of that late move was widely criticized, and Starr argued that Clinton’s delaying tactics were to blame. In political terms, it had the unexpected consequence of boosting Clinton’s popularity and indeed, the Democrats very unusually won congressional seats in those midterm elections.

But Starr is not likely to be Mueller’s model. Here, Comey provides a positive example: In 2016, his team finished the bulk of its work on the Hillary Clinton email investigation by June, his agents interviewed the former secretary of state on July 2 and he publicly closed the investigation on July 5.

Another high-profile precedent is the indictment of former Senator Ted Stevens on corruption charges in a year when he was on the ballot. The date: July 29.

So history suggests that Mueller should act by July—bringing charges or recommendations, or declining to act. Trump’s new lawyer, former New York Mayor Rudy Giuliani, asserted Sunday that Mueller’s team had told him its deadline was the end of August. Whether July or August, that is at most three months away.

What could happen in these three months? A lot. And that’s why it’s about to get interesting.

Mueller will interview Trump. Unless the president takes the Fifth. There is a debate, fomented by the president’s lawyers and by conservative legal commentators, over whether Trump will submit to an interview with Mueller’s team. But the legal precedent is crystal clear: He has no choice.

Presidents going back to Thomas Jefferson have submitted to court subpoenas. Presidents Grant, Ford, Carter and both Bushes provided testimony in criminal investigations or court matters. The Supreme Court in U.S. v Nixon unanimously held that a president could not resist a criminal trial subpoena to turn over the Watergate tapes. In 1998, the court ruled, again unanimously, in Clinton v. Jones that President Clinton could not claim immunity during his presidency from civil charges emerging from his private conduct. The court left it to the District Court to determine when and how the president could be called to testify, but there was no question that he could, and he was.

And if a president can be compelled to submit to a civil deposition and trial, then there is no question that he can be called in a criminal matter. Indeed, after Clinton v. Jones, President Clinton gave testimony not only in the civil case, but he spent almost six hours being grilled by independent counsel Starr’s team. In deference to the office and his schedule, Clinton testified from the White House, but the grand jury watched by live video feed from the courthouse. (I will pass over the irony that it was conservative lawyers who pressed for the unanimous Clinton v. Jones decision against Clinton, which now bites back against a Republican president.)

So why the loud claims from Trump’s lawyers and supporters that he need not submit? Consider it just public bargaining over the terms of the inevitable interview. Or consider it delaying tactics, to push into the dead zone past July where many a prosecutor would hesitate to act. Just this weekend, Giuliani suggested that the president may begin preparations—but not until after the June 12 Korea summit. He also insisted that Mueller first identify a confidential informant who may have spoken to outside campaign advisers. Also Sunday, Trump joined that call. For the president, delaying Mueller’s report past the November midterms would count as a substantial win.

But whether the talks fail or drag on, Mueller no doubt already has in his hand a signed subpoena ready to deliver. Like all federal grand jury subpoenas, it starkly directs: “YOU ARE COMMANDED to appear in this United States district court at the time, date, and place shown below to testify before the court's grand jury. When you arrive, you must remain at the court until the judge or a court officer allows you to leave.”

The president’s team truly does not want to receive that subpoena. Witnesses enter the grand jury room alone, without a lawyer, and must answer the prosecutors’ questions unaided. While the president would be free to step outside the room to consult with counsel, it is the nightmare of Trump’s lawyers that they will be outside a room in which he is being submitted to determined cross-examination. So no question, they will negotiate a compromise. Mueller will get his testimony.

Trump’s lawyers may also choose to litigate, both in hopes of achieving a Hail Mary court result, and in delaying the interview past Mueller’s July deadline. If so, they should recall that Clinton’s efforts to delay his own inevitable grand jury testimony formed a key part of Count XI of Starr’s recommended Grounds for Impeachment—so Trump might only be fueling the case for obstruction of justice by seeking a delay of his own.

If indeed compelled to testify, of course, the president also has the right of any citizen to cite his Fifth Amendment right to avoid self-incrimination. Here, the politics are brutal. To quote Trump himself from September 2016, “The mob takes the Fifth. If you’re innocent, why are you taking the Fifth Amendment?” Good luck on that one, Mr. President.

Paul Manafort will plead guilty in the coming weeks. The two indictments against Trump‘s former campaign, relating to his work for Ukrainian backers and his efforts to evade federal registration and to pay taxes on the proceeds of his work, are exceptionally strong. His junior partner in crime (and Trump’s deputy campaign manager) Rick Gates has already pleaded guilty and agreed to cooperate. And just last week, Manafort’s former son-in-law (and former business partner), Jeffrey Yohai, pleaded guilty and agreed to cooperate. There is little question, in prosecutors’ circles, that Manafort faces certain conviction and a long prison term.

Manafort at the moment is exercising his own Hail Mary defense: claiming that Mueller has exceeded his authority in charging him. That claim was roundly dismissed last week in the D.C. court, and in all likelihood the Alexandria court will follow suit. Rosenstein’s charge to Mueller to investigate allegations that Manafort “[c]ommitted a crime or crimes arising out of payments he received from the Ukrainian government” could not be more clear.

Once his Hail Mary motions fail, Manafort (and Mueller) will have every incentive to quickly reach a resolution. Manafort, who is 69, does not want to spend the rest of his years in prison. And Mueller needs to secure Manafort’s testimony and get his cases resolved before his July “deadline.”

With Trump’s interview in hand, and Manafort’s cooperation secured, we can expect that Mueller’s crack team will quickly finish the report or reports that they are doubtless already drafting.

And then, in or before July, the next chapter in this saga will unfold, also quickly: The delivery of reports to Rosenstein; the deputy attorney general’s decision whether to release the reports to the Congress and to the public; and the president’s efforts to prevent or delay Rosenstein from doing so. Whether those transpire on a weekend evening or not, Trump’s response could make the Nixon-era’s Saturday Night Massacre look like a moot court exercise.

Stay tuned. Air pockets ahead.