TV series Awakening of Insects tells the story of how Chen Shan (second from left), a street layabout in Shanghai, grows into a heroic underground Communist that risks his life to defend the homeland. [Photo provided to China Daily]

In recent years, it has become a trend for espionage TV series to cast young actors and actresses as characters who end up romantically involved as part of the plot to attract a wider audience.

Sun Hao, director of Awakening of Insects, points out that some handsome or beautiful actors might fail to deliver an emotional performance that the audience can relate to. Beauty can sometimes get in the way of authenticity.

Fortunately, Zhang, Sun says, has the depth of range to bring the audience and viewers with him.

"A high-quality spy drama should be based on a well-grounded storyline and relationships between the characters," says Sun. "After all, no matter how audiences' tastes change, they will always be attracted by compelling tales."

Zhang adds that a clear realization of a character, flaws and all, is important for the young performers like him.

"When judging my performance is successful or not," he says, "I would take into consideration not only whether the character is popular among viewers, but also whether my performance rationally presents a full picture of the character's personality."