Miranda Miles is a female assassin connected to wetwork jobs up and down the East coast of the US. She has worked for the Russian Mob, the Italian Mob, and the New Zealand Mob.
Her latest job was in the employ of Iran to take out Larry Duberman after he doubled the price of Manticore. She is an attractive brunette who uses her beauty to get close to her targets; in this case, seducing Nate to lead him away and lock him in the broom closet, then flattering Larry's ego in order to lead him away from Sophie at the high school reunion.
Interpol has a file on her and consider her to be armed and dangerous. She has had training in martial arts but the fact that Sophie got the better of her suggests she doesn't practice much, she relies too heavily on her beauty to get close rather than fighting through bodyguards, or Sophie is a better fighter then we have been led to believe so far. When she got Larry away from the reunion she intended to kill him with a silenced pistol. It is clear she is proud of her reputation as she wouldn't accept Larry's offer of paying her double what the Iranians were if she didn't kill him.