Shaitani Ilaaka

A grotesque brougham stops in a dark forest and its cowled driver, Lalbai the sorceress, beckons to the bewitched passenger, a newly wed bride. Lalbai leads the bride to the shaitani ilaaka (devil's domain) where she is roused from her spell. The bride is sacrificed, screaming and kicking, at the altar of her aka (the Shaitan, or great devil). Shaitan is an ancient and fearsome demon. Years ago, he roamed free and indiscriminately terrorized the local townsfolk. But he was ultimately defeated, reduced to a formless soul, and held, by a magic charm, to remain imprisoned forever within the shaitani ilaaka. Lalbai brings him a fresh bride every Amavasya night. Shaitan consumes the blood of this bride, and grows stronger with each offering, until he can break the charm, restore all his evil powers and ravage the world again.
At the affluent home of rich industrialist Thakur, he has a wife, Roma, and their six-year old daughter, Anju. They have retained a governess, Shalaka, for Anju. Anju seems to be a happy child with one exception. She experiences strange convulsions and horrible nightmares every Amavasya night. Thakur decides to bring her to Dr. Yograj, a medical man who has attained Siddhi through rigorous spiritual training. Dr. Yograj examines Anju from a medical standpoint, but also notices strange telekinetic events when Anju is in his office. Later, at the home, he observes phenomena that strongly indicate a poltergeist. When he talks to Shalaka, she firmly snubs him. (Unbeknownst to the family however, Shalaka practices voodoo with Anju as the target.)
Dr. Yograj refers Thakur to a famed Tantrik Baba (wise man), recently returned from Tibet after an extended spiritual course, for help. Baba visits the home, inspects Anju's room, and immediately identifies it as the work of a malevolent aatma (soul). He advises Roma to remove Anju from the home, take her far away, and have her recuperate. This must be done at the brahmakaal (good time, when the powers of evil are weakest). Anju's boyfriend Deepak and their friends come together to take her away.
Shalaka is outraged at Anju's removal. She steps way out of line and demands to know Anju's whereabouts. Roma refuses and puts her in her place, whereupon Shalaka transforms into a hideous witch, Lalbai, and attacks Roma. She reveals she has served Shaitan for ages, and when Thakur's ancestors used various magic incantations to defeat Shaitan, she infiltrated Thakur's household as a governess. She hopes to use Anju, the living descendant of Shaitan's enemies, as the final sacrifice to liberate Shaitan. She intercepts Deepak and proceeds to attack him. But Baba arrives on the scene and engages Lalbai in a violent magic confrontation. Baba manifests an enchanted stake, and skilfully distracts Lalbai until Deepak drives the stake into her. Impaled by the charmed stake, Lalbai loses her mortal form and is transformed into a vulture forever.
Deepak and his friends successfully remove Anju to a safe haven away from the city. They take the opportunity for some rest and relaxation. Baba tracks down Lalbai to the shaitani ilaaka. He uses his spiritual powers to summon her. When he discovers her intentions with Anju, he swiftly realizes Deepak and Anju must marry and consummate their matrimony as quickly as possible. Deepak and Anju are deeply in love and would marry anyway, they hasten the event and obtain a marriage license with Baba and others as witnesses.
Lalbai does not give up. She rounds up a bunch of henchmen, hypnotizes them as zombies, and through them, invokes her voodoo powers to summon (the now married) Anju to the shaitani ilaaka to be sacrificed to Shaitan. Deepak and his friends arrive midway through the ritual. They break up the evil ritual, beat off the zombies, and rescue Anju. Baba goes into the shaitani ilaaka to put an end to Lalbai and Shaitan.
Baba and Lalbai engage in another vicious battle. Lalbai reveals that Anju's blood reached Shaitan (during the botched sacrifice) and that Shaitan has recovered enough of his powers to be able to leave the ilaaka temporarily. Baba kills Lalbai in the conflict, but is immediately attacked by Shaitan. With most of his powers consumed in the battle with Lalbai, Baba ultimately succumbs to Shaitan.
Shaitan begins venturing out of the ilaaka and ravaging the village again. The villagers observe that Shaitan was resuscitated only after Deepak (and Anju) arrived. The frightened and ignorant village folk decide to sacrifice Anju (and tie up Deepak and his friends so they should not cause hindrance) to Shaitan, hoping it will appease the devil back into slumber.
The final confrontation occurs near the village square where Anju, lashed to a pillar, is used as bait for Shaitan. As the growling Shaitan gleefully steps up to exact his vengeance, Deepak breaks free and attacks Shaitan. Shaitan fends him off with a powerful blow that pitches Deepak halfway across the square into a Kali mandir (temple honoring Goddess Kali). Deepak snatches a trishul (holy trident of Kali), discovers it repels Shaitan, and ultimately drives it into Shaitan. The powers of Kali, channeled through the trishul, destroy Shaitan and bury him deep into the ground for ever. The entire village is relieved with the blessings of Mata (another appellation for the mother Goddess Kali).
source: Wikipedia

Question: Lalbai infiltrated Thakur's household as what?
Answer: A governess