political expert, he's also a history buff. a best-selling author. a new book out tomorrow. "three days in moscow." bret baier joins us tonight. >> thanks for having me. >> tucker: doug brinkley, one of the most famous, may be the most famous reagan historian calls this one of the best and most essential books ever written about ronald reagan. i'm impressed. >> and i didn't even pay him. >> tucker: it's amazing. three days. sort of boiled down the pivotal moment to three days. what three days? >> is the three days of the fourth summit between reagan and gorbachev where reagan goes to moscow and he meets with gorbachev. they are finalizing the nuclear arms treaty, but he also gives an uncovered and overlooked for the most part speech to moscow state university students and takes q&a from them. we use three days to jump back and look at how reagan gets to this point and really leads to