WASHINGTON — A week ago, the F.B.I. director, James B. Comey, jolted the presidential race by sending a letter to Congress saying the bureau had discovered new emails that might be relevant to Hillary Clinton’s use of a private server. The disclosure set off widespread criticism of Mr. Comey and unleashed a hurricane of news about Mrs. Clinton’s family foundation, Russia and F.B.I. infighting. Let’s sort it all out.

What exactly is the F.B.I. investigating?

The F.B.I. obtained a search warrant this weekend to begin analyzing emails from one of Mrs. Clinton’s closest aides, Huma Abedin. Agents seized a laptop belonging to Ms. Abedin’s estranged husband, Anthony D. Weiner, on Oct. 3 as part of an investigation into whether he exchanged illicit text messages with a 15-year-old girl. Investigators want to know if Ms. Abedin’s emails will change the conclusion Mr. Comey announced in July: No one in Mrs. Clinton’s inner circle should be prosecuted for mishandling classified information.

Agents and analysts have loaded Ms. Abedin’s emails into a computer program that allows them to identify those they have already read and whether any they have not seen before might contain sensitive national security information.