"Fantastic Beasts and Where to Find Them" takes place in New York City in the early 1920s, at the height of the Great Depression, when "normal people" are seen as something of a rarity. The young man who has just returned from a world-traveling trip, Newt Scamander, has just completed a world-wide trip to locate and document magical animals. Arriving in New York City for a short stopover, he may have just come and left without incident, but when he stumbles upon a magical case that contains a key to the most powerful and mysterious of all magical creatures - a black unicorn called "the Weasel" - he may have just come and gone as gracefully as he arrived.
When Newt Scambold (Eddie Redmayne), a first-year wizard at Hogwarts School of Witchcraft and Wizardry, arrives in New York, he is met by Jacob - a No-Mage (non-magical person with no magical ability). Although the wizard is initially wary, Jacob introduces him to "a friend of his," Fudge (Rex Gordon), who is the Minister of Magic. The Minister, a first-year student at Hogwarts, is impressed with the fact that Newt is able to leave his house in the morning without fear for being chased by "muggles," the term used for non-magicals. As Fudge and Newt become close friends, they soon become concerned about Newt's safety.
Once they learn of Newt Scambold's ability to leave home safely, they begin searching for him everywhere they can. First they start by asking around their school, to make sure that Newt is in good company, but the No-Mages are uncooperative and eventually they begin to follow them wherever they go. One night, Newt and Fudge accidentally stumble upon a wizarding newspaper featuring the story of a "Wizarding Exchange School" and find themselves drawn into this world of magic.
While there, Newt and Fudge run into a variety of fantastical creatures, many of which seem to be after them. The film ends with Newt and Fudge running into a group of "big bad wizards." After an extended chase, the pair get away, but Newt is bitten by a werewolf - one of the more powerful creatures in this world - and Fudge is left in the hospital with a serious case of lycanthropy, a condition caused by a transgression of blood.
Newt is taken away by a wizard who takes him to a wizarding prison, "The Leaky Cauldron," and told that he must help him in a mission that will allow him to join his fellow students in "exchanging ideas," and fight "the greatest wizard of all time." Newt, unaware that he's actually in a prison designed to hold and house a powerful creature that can control time itself, begins to fight back. The film ends with Newt and Fudge escaping and heading back to the Leaky Cauldron to save their friends and end their misery. They return to the wizard who has provided them with a map of the location of the exchange; they enter the room and Newt realizes that Jacob and the No-Mages are working with the wizard.
The film features a number of supporting characters such as Jacob's wife, Rosemary, and a couple of who work at the Ministry, as well as a few minor wizarding figures who include a female witch named Filius Flitwick and a male wizard named Pius Thick-Skinned, who is a student of the Harry Potter series. There is also a secondary character who serves as a mentor for Newt and is later revealed to have been a werewolf - though it's never explicitly revealed whether or not he actually is a werewolf or not.