All of the first season, summed up.
Blind lawyer Matt Murdock is tired of all the crime and injustice in his city, and decides to do something about it. He decides to put martial arts training and his enhanced senses to good use and starts prowling the streets as a vigilante wearing a black mask at night, while by day he is busy starting up his new law firm with partner and long time friend Foggy Nelson.
The first case for Nelson and Murdock is to come to the defense of accused murderer Karen Page, who swears she is innocent. Between Matt’s efforts as a lawyer and as a vigilante, they are able to clear her of charges, but are tipped off to a larger conspiracy in Hell’s Kitchen. The danger worsens as the Man in the Black Mask makes enemies among the city’s criminal element, causing trouble for the Russian drug runners and for corrupt company Union Allied.
Unknown to Matt, he has stepped his foot in a massive criminal undertaking that is bringing together the Russians, the Yakuza, and the Chinese, all under the umbrella of a mysterious criminal Kingpin. Matt’s fight, both on the streets, and in the courts against the remains of Union Allied, shake up the organization, and bring them to question the Kingpin, forcing him to take action. He cuts out the disloyal Russians, taking over their part of the operation himself, and attempts to send Yakuza ninjas to kill the vigilante.
When Matt and Karen, with the help of reporter Ben Urich come close to exposing the Kingpin, Wilson Fisk, he steps out ahead of them, and goes public with his vision of remaking the city. With no solid proof of Fisk’s criminal undertaking, Matt and the others are forced to back down, but Matt continues to go after Fisk’s operation in the shadows as the danger to everyone they know escalates.
Finally, when his accountant betrays him, Fisk is left vulnerable, and Matt is able to get the evidence that they need for Nelson and Murdock to put Fisk away. He is able to escape custody, but the vigilante is there to stop his escape, putting him behind bars, and gaining the moniker of Daredevil.