Not all superheroes wear capes. Some wear green rubber boots and sell fresh seafood at a wet market.

For the past three years, Madam Mai Thi Thien Thanh and her 50-year-old husband Kang Eng Hiang - a couple who run a small stall at Geylang Serai Market - have opened their modest Marsiling Housing Board flat to Vietnamese families with children who are seeking medical help here. They even provide them with home-cooked Vietnamese meals.