Nur Kasih is a story of two brothers, Aidil (Fizz Fairuz) and Adam (Remy Ishak), who are polar opposites: the former is a pious man who is respectful to his parents while the latter is a lost soul, living in Sydney, Australia as an architecture student. Since their childhood, Aidil has always been more responsible than Adam and he has the full trust of their parents, Ustaz Hassan and Hajjah Khadijah.
The village's imam, Ustaz Abu Bakar, has two daughters - Nur Amina (Tiz Zaqyah) and Siti Sarah (Ummi Nazeera). Nur is the best student in the village and has high hopes to continue her post-secondary education despite the family's poor finances, even applying for a scholarship (and was accepted) to study at the International Islamic University in Kuala Lumpur. But fate turns ugly when the family received a visit from Ustaz Hassan.
Unbeknown to his family, Ustaz Hassan has been suffering for years and it has taken a toll on him. We see the doctor telling him that he does not have long to live and to prepare for his going; the family calls their sons back home. Aidil who was studying in Al-Azhar University in Cairo, Egypt willingly went home but Adam was a bit reluctant to leave Sydney and his girlfriend, Katrina (Sharifah Sofia).
In Malaysia, the brothers return home to their dying father. Adam is grumpy and frequently lashes out at his family, blaming them for his being stuck in a village. Their father expressed a wish to see at least one of his sons married and asked Aidil if he had someone in mind. Without missing a beat, Aidil replied that he indeed had someone he was interested in: Nur Amina. Ustaz Hassan, however, had a different idea. On the day of engagement, he surprised them all with the decision to court Nur Amina not for Aidil, but for Adam. Even though he was disappointed, Aidil accepted his father's decision and tried to understand his father's wish to help Adam.
On their wedding night, Adam lashes out at Nur, saying that their entire marriage was a sham. He even insists that the marriage was her fault because whilst he had no choice but to follow his dying father's last wish, she had the choice to say no but she did not. He insults her further by saying that she is not his type.
After the death of Ustaz Hassan, Adam decides to return to Australia and leave Nur. Unwilling to bring shame to her family, Nur decides that she will leave the village and deceive her parents by saying she has gone to Australia but actually going to Kuala Lumpur. She sought the help of her old friend Nabila and enrolled in the International Islamic University, studying architecture. Aidil insisted on helping her but Nur refused, saying that it was better for everyone if nobody knew where she was. She continued living a lie for five years, completing her degree and working in an architectural firm in Kuala Lumpur.
Adam, on the other hand, lives a life of sin in Australia. Upon reaching Sydney, he was seen partying and going out drinking with his friends and girlfriend, Katrina (Adam is a Muslim and as such, drinking alcohol is a sin). He eventually proposes to Katrina, who had no clue that he had been married previously. Adam was promoted to vice-president of his architectural firm while Katrina found out she was pregnant. All was good in the southern hemisphere, but tragedy strikes when in the eighth month of pregnancy where Adam and Katrina gets into a car accident (brought on by Adam's drunk driving). As a result, Katrina lost her baby and Adam was sentenced to prison.
In prison, Adam reconnects back with his religion and reforms himself to be a better man. Pondering upon the life he had before prison, in which he sees as meaningless, he decides to bring Katrina back to Malaysia upon his release so that they would both go back living "on the straight path".
At the same time, Nur is grieving after her homesickness. Deciding that the charades was over, Nur headed on back to her village and was intent on telling her parents the truth about the last four years. As she was about to, she had a call from Aidil saying that Adam is coming home too.