Koi... Mil GayaSave

In Kasauli, Himachal Pradesh — a small mountain town in northern India — Rohit Mehra (Hrithik Roshan) lives with his mother Sonia (Rekha) and his deceased father's house. Rohit, who has special needs due to a childhood accident, is mocked by his community as childlike and incompetent. His father — a brilliant scientist who died in a car accident shortly after Rohit's birth — had been working on cosmic-radiation experiments that may have contributed to his death. The opening establishes the franchise's primary emotional anchor: Rohit's gentle character and his community's casual cruelty.

Rohit's mother Sonia is the franchise's primary moral anchor; her commitment to her son's well-being despite community criticism is the franchise's primary character-development arc. Sonia is depicted as a working-class single mother who has dedicated her life to raising Rohit; her commitment to him is the franchise's primary emotional touchstone. Rekha's performance combines substantial dramatic gravitas with quiet maternal warmth; her on-screen presence is widely cited as the franchise's most-effective emotional anchor.

Rohit discovers his father's old research equipment in the family attic. He activates the equipment — a series of cosmic-radiation transmission devices — and inadvertently sends a signal to space that attracts an alien intelligence. The alien — eventually named Jadoo by Rohit — descends to Earth in a small spacecraft that lands in the Kasauli cornfield outside the Mehra family's house. Jadoo is depicted as a friendly, intelligent, communicative being with elaborate technological capabilities.

Jadoo and Rohit develop a deep friendship — the franchise's primary character relationship. Jadoo, recognisizing Rohit's special-needs condition, uses his alien technology to gradually heal Rohit's cognitive disabilities. Over weeks of secret interaction, Rohit's intelligence and physical capabilities are substantively elevated; he becomes capable of normal adult-level functioning, with substantial enhancements in mathematical and physical skills. The transformation is treated as the film's primary character-development beat.

Rohit's transformation is initially hidden from his mother; he gradually reveals his enhanced capabilities. His relationship with Nisha (Preity Zinta) — a young woman from a wealthy family who has been visiting Kasauli for the summer — gradually develops from one-sided affection to mutual romantic interest. Nisha's gradual acceptance of Rohit's transformation provides the franchise's primary romantic subplot; her commitment to him despite his social marginalisation is widely cited as the franchise's most-effective character-development beat.

Local authorities and a corrupt scientist named Dr. Arya (Rajat Bedi) discover Jadoo's existence. They want to capture the alien for research purposes; their pursuit becomes the franchise's primary antagonist threat. Rohit and his community must defend Jadoo from the kidnap attempts; the film's middle act consists of multiple chase sequences and evasion narratives. The community's commitment to protecting Jadoo despite the kidnappers' substantial resources is widely cited as the franchise's most-effective community-based action element.

Jadoo and his alien comrades return for him at the film's third-act climax. The franchise's primary emotional moment — Rohit's farewell with Jadoo — is the franchise's most-cinematic moment. Jadoo, before departing, leaves behind a permanent enhancement to Rohit's biology; this enhancement will eventually be inherited by Rohit's son Krishna in the subsequent Krrish films. The franchise's continued narrative continuity across multiple subsequent films is established by Jadoo's farewell gesture.

The film's epilogue shows Rohit and Nisha's relationship formalised; Rohit's continued life in Kasauli with his now-restored cognitive abilities; and the franchise's primary plot thread established for future expansion. The film's massive commercial success — US$8 million in 1987 — directly secured the production of Krrish (2006) three years later.