What is the fine-grained topic of the following text: The flight conveying former president Nawaz Sharif and Maryam Nawaz arrived at Lahore's Allama Iqbal International Airport around 8:45pm PST on Friday night, and the two were arrested by National Accountability Bureau (NAB) authorities around 9:25pm. Only return the topic.
Arrest of former president Nawaz Sharif and Maryam Nawaz upon arrival at Lahore's Airport