This is apparently a pair of Kahaani remakes (in Tamil and Telugu) from the director of Godavari, etc. He has no experience with thrillers but has a gift for creating interesting female characters and getting good work out of his actors. Personally, I felt that Kahaani was a better character drama/travelogue than it was a thriller, so I don't really have a problem with that.
Nayanthara is one of the more established actresses on the Tollywood/Kollywood circuit; the only thing I've seen her in were very male-centric movies like Billa (Ajith) and Aadhavan, where she did well with what she was given. Box office analyst/journalist/alleged reviewer Taran Adarsh posted a couple of pics from the movie:https://mobile.twitter.com/taran_adarsh/status/330278012186656768/photo/1https://mobile.twitter.com/taran_adarsh/status/330281466586071043/photo/1