Harikatha is an art form in which the peformer "bhagavatulu / bhagavatarani" tell stories from Indian mythology, puranas, itihasas etc. interspersed with melodious songs and poems. This art form is popular all over south india. For more information refere here. The most famous Telugu Harikatha exponent is Ajjada Adibhatla Narayanadasu.
This was clicked in a Harikatha Saptaham (Seven day festival) at the New Nallakunta Ramalayam, Hyderabad.