the heising simons foundation, unlocking knowledge, opportunity, and possibilities. more at hsfoundation.org. and by the frontline journalism fund, with major support from jon and jo ann hagler. and additional support from laura debonis. ♪ ♪ (people talking in background) (bomb bursting) >> breaking news this morning. explosions were heard... >> russia has the troops to invade with overwhelming force. >> it's war. >> narrator: on february 24, russia attacked kharkiv, ukraine's second-largest city. (explosion bangs) many expected the city to fall in days. >> irina (speaking russian): >> man (speaking russian): >> narrator: but the ukrainians refused to surrender. (boy imitates explosion) >> (speaking russian): (gunfire pounding) >> narrator: filmed over the first three months of the war, this is the story of the battle for kharkiv, told by the people who living through it: the displaced families... >> (speaking russian): >> narrator: the civilians caught in the fight... >> man (speaking russian): >> tatyana (in russian): >> narrator: and the first responders who r