Gair is the story of an illegitimate child . He grows up to become Vijay (Ajay Devgan), under the guidance of Mr. C.K.Oberoi (Amrish Puri).Vijay, who becomes a very successful businessman, falls in love with Madhu, (Raveena Tandon), daughter of Judge Amarnath (Satyen Kappu) . A love triangle develops among Raja, the son of Mr.Oberoi, Vijay and Madhu. Taking advantage of Raja's linking toward Madhu, his maternal uncle , Jagat Mama,(Paresh Rawal) tries to create a rift between father and son.
Then there is a twist in the tale. Sharda (Reena Roy) who is Raja's mother, comes to know that Vijay is no other then her own son from Ajay Devgan, the air force officer, who died in a road accident. Towards the end, all become one family , after a sequence of fight sequences.