Riddle) is a 1997 Indian Tamil-language romantic drama film written and directed by Agathiyan, and produced by Kavithalayaa Productions.

The film stars Prakash Raj and Neena, while Manivannan and Janagaraj appear in supporting roles.

Anandhi is a seventeen-year-old college student who lives with her widowed father, Ramanadhan, a psychiatrist who twice suffered heart attacks.

Almost after a month of her father's death, Anandhi is visited by Neelakandan, a single former Army man in his early 40s.

Vijayan tells Neelakandan how he caught his wife cheating with one of his employees whom he tried to fire, framing him for theft to avoid the disgrace.

Neena, a former child actress in Keladi Kannmanii (1991), was selected for the lead role in Vidukathai when she was still at school and had to work on her schedules around exams.

[1] The production of the film was hampered by the FEFSI strike of 1997 and the makers had to postpone the venture from its original scheduled release date of June 1997.

[6] Ji of Kalki wrote Agathiyan who kept the masala elements away has also kept aside the idea of keeping the message clear and complete which are major obstacles to the flow to the film, he however praised the performances of Prakash Raj, Neena, Janagaraj and Manivannan but felt whether audience could able to understand the concept and psychology of this film.