Each week — and some days, it seems, each hour — brings more clarity to the picture of the Ukraine affair and the political crisis it sparked in Washington over impeachment.
But some of the biggest questions still don't have answers.
Here's a look at where the saga stands, what investigators want to learn and what major decisions still must be reached before the fever breaks.
The Ukraine affair
No one disputes the basic outlines of the Ukraine affair, including President Trump:
He used a combination of personal aides and official State Department diplomats to pressure the government of Ukraine to launch investigations into the family of former Vice President Joe Biden and a conspiracy theory about the 2016 cyberattacks against Democrats.
The White House says it sees no problem.
Trump has cited what he has called his responsibility to investigate "corruption," referring to the Biden family. And acting White House chief of staff Mick Mulvaney said on Thursday that foreign policy is always political, diplomats work for the president and that everyone needs to "get over it."
Democrats say all this is not only improper but also could be grounds for impeachment. Trump invited another foreign government to interfere in another U.S. election, they argue, and defied the will of Congress by halting military assistance to an ally, in Ukraine, against an adversary, in Russia.
Many Republicans in Congress, meanwhile, have blasted what they call Democrats' "illegitimate" impeachment inquiry. And a handful of Trump's supporters have said that although they believe the president's actions weren't appropriate, he shouldn't be impeached.
Question 1: How involved was Trump?
House Speaker Nancy Pelosi, D-Calif., has commissioned three committees to investigate. A stream of witnesses have been appearing for closed-door depositions in the Capitol.
Much of what they've said is not yet public, but the narrative that has formed is about an effort driven by Trump's personal lawyer Rudy Giuliani and including Mulvaney and Secretary of State Mike Pompeo.
There's no question that Trump also was involved and that it was Trump who asked Ukraine's president for the investigations in a now-famous July 25 phone call.
But did Trump plan and organize the Ukraine pressure strategy himself? Did Giuliani pitch it to him? How involved was the president in carrying it forward?
What Trump knew and did, and when — whether he admits it or investigators build a case based on witness testimony — could bear significantly on how Congress and Americans decide to respond.
Question 2: How much more investigating will Democrats do?
A fog of unreality has accompanied the fast-moving Ukraine affair, among other reasons, because it seemed to flash nearly fully formed into public understanding.
As Mulvaney said Thursday, people in Washington expect there to be a cover-up — but the administration has admitted many of its actions. He acknowledged that Trump expected concessions from Ukraine's president and he also pointed out that Trump has released the account of his phone call.
Neither Trump nor Mulvaney, in short, are hiding or apologizing. What's there is there, they've said.
And even though the White House said it wouldn't cooperate with impeachment, many witnesses keep appearing in Congress, including the U.S. ambassador to the European Union, Gordon Sondland, who testified on Thursday even though he previously was barred from doing so.
Pelosi and House Intelligence Committee Chairman Adam Schiff, D-Calif., have said they must learn more and conduct some hearings in public before the House approaches the point of a vote to impeach Trump.
But with so much of the story now told, how much of that further investigation is about necessity and how much of it is a play for time?
What impeachment means
Impeachment in the House is an indictment that would spur a trial for Trump in the Senate. The president's Republican allies control the upper chamber, and he appears to enjoy more than enough support to retain his office.
Pelosi, Schiff and their allies also can see that when impeachment leaves the House, they lose control and the saga shifts into a new phase with different political implications.
So how much of the pending investigation is about accumulating information — and how much of it is about keeping the story alive while Democrats still can? And how much is about staving off the point at which Democrats must decide how to act in light of all that has been revealed?
Question 3: Will the House vote to formally initiate the impeachment inquiry?
Trump and his Republican supporters argue that impeachment isn't real unless the full House gets to vote. Pelosi observes that the Constitution gives her broad discretion about how to handle the matter and that she can proceed as she has.
The speaker was asked this week why, if she believed she has the support in the House, she wouldn't just convene a vote and call Trump's bluff, as a reporter put it. Pelosi didn't address that directly, but she did say that Democrats remains serious and that this isn't a "game."
Pelosi resisted calls from her most liberal members to pursue impeachment for months, mindful about the need to continue to reach moderate voters to defend her majority and run alongside Democrats' presidential nominee next year.
When the outlines of Trump's Ukraine pressure strategy became public, that moved so many Democrats that the speaker had no choice but to move with them and announce that the House had moved into the impeachment inquiry.
Proceeding without a recorded vote is a way for Pelosi to keep her options open. If impeachment becomes a political loser, she and Democrats could back away without having opened a door they might be expected to then close with a difficult vote on impeachment itself.
But some polls have suggested that public opinion may be moving the Democrats' way on impeachment and even removal of Trump.
If the speaker and Democrats feel they're standing on solid ground, they might convene a vote by the full House to launch impeachment as a way to undercut Republicans' arguments about its illegitimacy. That also might make the momentum unstoppable toward articles of impeachment.
Question 4: Would Democrats go through with a vote to impeach Trump?
Democrats have been talking about impeachment for years. Possible cases have included Trump's immigration policies, the Russia imbroglio and Trump's ongoing business dealings. On Thursday, Mulvaney said Trump would host next year's Group of Seven summit at his own golf resort in Florida.
But Democrats' previous impeachment discussions never went forward — in large measure because Pelosi held them back.
The old conventional wisdom was that an impeachment process that results in a Senate acquittal would wind up hurting Democrats and helping Republicans.
A party-line vote that resulted in Trump keeping his office would be seen as a vindication and acquittal in this line of thinking, and voters would punish Democrats in the way they punished Republicans after President Bill Clinton was impeached in 1998.
Today, Pelosi argues that House Democrats are taking a stand based on principle and that a president cannot solicit foreign interference in U.S. elections or defy Congress. She and the House majority are contemplating what would only be the third impeachment vote in history for a sitting president.
Would Pelosi only take that step if she feels the political landscape had changed enough that she could do so safely?
Or would she trigger the Senate trial even if she believed it would damage her own party politically — or, even more consequentially, remove a president within a year of the day that voters expect to have their own say in the matter?