In the series, Zheng is depicted as having a close friend, a local doctor who is also named Gassimou. The character speaks Chinese fluently and loves Chinese culture-one of his favorite music works is the Chinese violin concerto Butterfly Lovers-and he occasionally "shows off" his cooking skills of Chinese cuisine in the likes of stir-fried eggs and tomato, one of the easiest and most popular dishes on Chinese people's dining tables.

There are two numbers in the series that have also stirred Cao's memory of his time in Guinea. The protagonist's badge on his white hospital uniform is "3281", close to Cao's own "3481" on his uniform, both in Beijing and Conakry. The first infected patient in the TV series is treated in the No 18 hospital cot, same as the bed number of the first diagnosed Ebola case at the China-Guinea Friendship Hospital, where Cao worked in 2014.

"The TV series has done a delicate job in re-creating a lot of details, making me, a person who has experienced the epidemic, feel that it is realistic and relatable," says Cao.

Aside from nerve-racking scenes that show doctors racing against time to save lives, the drama provides an exotic look at the daily lives of the locals, ranging from bustling street markets to distinctive ceremonies.

Chief producer Mao Yi says she had the idea to make the series after watching the four-episode documentary Border for Doctors in 2018. The documentary chronicles how China sent more than 21,000 medical workers to Africa over the past 55 years.

To do a comprehensive preparation for the new series, its major creators traveled to Tanzania and Sierra Leone in early 2019, and interviewed nearly 100 experts and medical workers, making notes of around "10 million words" over three years, according to Mao.

After joining the project in June last year, director Yang Wenjun and his team paid visits to hospitals and research institutions in Beijing, and Shenzhen and Guangzhou in Guangdong province, obtaining more firsthand information from top experts, including Li Jin and Qian Jun, two leaders of a Chinese medical team dispatched to Sierra Leone in September 2014.