The Case of the Love Commandos is 4th in the Vish Puri mystery series by Tarquin Hall. I came across one used, and now I pick them up as I see them. The characters are a lot of fun, and the plots of these tend to include interesting local color and information on the history and culture and traditions of India. The detective has his own website here.
from the back of the book:
Vish Puri fights for love in a modern-day Romeo and Juliet.
When Ram and Tulsi fall in love, the young woman's parents are dead set against the union. She's from a high-caste family; he's an Untouchable, from the lowest stratum of Indian society. Fortunately, India's Love Commandos, a real-life group of volunteers dedicated to helping mixed-caste couples, come to the rescue. But as soon as they free Tulsi from her father, Ram mysteriously disappears. It falls to Vish Puri to track him down. Unfortunately, Puri's having a bad month. He's failed to recover a stolen cache of jewels, and his wallet was stolen, forcing him to rely on his Mummy-ji to get it back. Worse yet, his archival, suave investigator Hari Kumar, is hot on the case as well. In the daring race to find Ram, Puri and his team must infiltrate his village and navigate the caste politics shaped by millennia-old prejudices.
I've also read these:
1) The Case of the Missing Servant (2008)
2) The Case of the Man Who Died Laughing (2010)
3) The Case of the Deadly Butter Chicken (2012)