Sanak is an action-thriller film, summarizing the emotion and journey of a lone hero, who fights overwhelming odds in a restricted environment, to save his wife and other unfortunates, helpless hostages, from the perils of evil. Vivaan Ahuja, a skilled MMA trainer, learns that his wife Anshika Maitra's heart can stop at any time and an operation is required. The operation is successful. As she recovers in the hospital, a terrorist group led by Saju Solanki attack the hospital to retrieve their illegal arms dealer and leader Ajay Pal Singh. Ajay was actually responsible for the deaths of 18 INA soldiers due to his supply of faulty weapons and was moved to the hospital for emergency surgery after his pacemaker was tampered with in prison. Patients of the hospital are taken hostage, including Anshika, while Ajay is unconscious under anaesthesia after his surgery.
ACP Jayati Bhargav and her team are tasked to free the hostages. Vivaan, who is just leaving after visiting Anishka is in the hospital basement, oblivious to the invasion until he is attacked by one of the terrorists. He manages to kill the terrorist. Shocked, he takes the black pouch belonging to the terrorist, which contains a walkie talkie and a remote detonator and sneaks back into the hospital. He meets a hospital guard named Riyaz and a child named Zubin who had been hiding, and befriends them. Meanwhile, Jayati is stunned to see that her daughter Aanya is being used by the terrorists, strapped to a bomb. Saju blackmails her, saying that he will blow up the hospital unless she supplies a chopper and a bus to them.
