Three-year-old Polina has neuroblastoma – a rare type of childhood cancer.
Her expensive treatment is running out. Her mother faces a dilemma – should the family stay in their basement for safety, or risk going outside to try and flee Kharkiv and get help for their daughter?
Warning – this video contains distressing footage of an explosion in Freedom Square, Kharkiv. It has been verified by the BBC but the source is unknown.
Video by Sarah Rainsford, Ellen Tsang, Tony Brown and Lindle Markwell