Paul Singer, and Cooper Allen

USA TODAY

The second Trump-Clinton presidential debate began icily — the two candidates nodded to each other upon arriving on stage, but did not shake hands — and very quickly turned fiery. Here are some of our top takeaways:

Trump went there

At the first debate, Donald Trump said he could have raised the issue of Bill Clinton's past infidelities, but he resisted. On Sunday night, he unloaded. “What he’s done to women, there’s never been anyone in the history of politics in this nation who has been so abusive to women,” Trump said, and “Hillary Clinton attacked those same women and attacked them viciously.”

He even invited some of Bill Clinton's accusers, such as Paula Jones and Juanita Broaddrick, to attend the debate and held a news conference, of sorts, before it started where they denounced the Clintons.

Clinton basically ignored the attack entirely. "So much of what he just said is not right," Clinton said, "But he gets to run his campaign any way he chooses. He gets to decide what you want to talk about." She then quoted Michelle Obama: "When they go low, you go high." But the high road consisted of noting that Trump has never apologized for attacks on various people and groups including the Kahn family, the Gold Star parents who spoke at the Democratic convention.

And then it got uglier

Trump said Clinton was the one who should apologize for destroying 33,000 emails from her private email server. "If I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation because there has never been so many lies, so much deception. There has never been anything like it," Trump said.

Clinton responded that "everything he just said is absolutely false. ... It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country."

"Because you'd be in jail," he shot back.

It's not often you hear one presidential candidate threaten to launch an investigation of their opponent at a nationally televised debate. Actually, it's unprecedented.

Trump-Clinton debate stays angry until the very end

Analysis: She called him a misogynist. He said she should go to jail.

Trump says he did not grope women

Yep, that is the 2016 presidential campaign in a nutshell. Moderator Anderson Cooper made note of the 2005 video released last week in which Trump is caught on a live mic saying he kissed women without their permission and grabbed them by their genitals and got away with it because he's a celebrity.

Trump said several times it was just "locker room talk" and while he is not proud of it, there are more important issues to discuss. Cooper asked directly whether Trump had ever actually done any of those things, and Trump was slow to issue a flat denial. When he did, it was in passing: "Women have respect for me. And I will tell you, no I have not, and I will tell you that I'm going to make our country safe. We’re going to have borders in our country, which we don't have now."

Employing again the "locker room talk" defense is likely not what many Republican leaders were hoping to hear from their nominee.

Trump-Pence: It's complicated

Another first for a presidential debate: Donald Trump said his running mate, Mike Pence, is wrong about Syria.

Moderator Martha Raddatz asked how Trump would handle Syria, noting that Pence said "provocations by Russian need to be met with American strength and that if Russia continues to be involved with airstrikes (against rebels) along with the Syrian government forces of Assad, the United States of America should be prepared to use military force to strike the military targets of the Assad regime."

"He and I haven’t spoken and I disagree," Trump said. "We have to knock out ISIS. Right now Syria's fighting ISIS. We have people that want to fight both at the same. But Syria's no longer Syria. Syria’s Russia and it’s Iran. ... We have to worry about ISIS before we can get too much more involved."

While U.S. policy has been to work with rebels to topple the Syrian government of Bashar Al Assad, Trump said "you don’t even know who the rebels are."

Trump openly disagreeing with Pence over a key foreign policy issue comes one day after Pence said in a statement he was "offended" and could not "defend" Trump's comments in the 2005 recording, and some Republican officials openly called for the Indiana governor to replace Trump on the ticket.

But hey, nothing to see here, right?

You, Madam Secretary, are no Abe Lincoln

Clinton, asked about newly released speech transcripts in which she admitted taking different positions on issues in public and in private, said it was Abraham Lincoln's idea first. As depicted in the movie Lincoln, "President Lincoln was trying to convince some people, he used some arguments, convincing other people, he used other arguments," Clinton said. "That was a great — I thought a great display of presidential leadership."

Trump scoffed. "Now she's blaming the lie on the late great Abraham Lincoln," he said. "Honest Abe never lied. That’s the good thing — that's a big difference between Abraham Lincoln and you."