“9-1-1: Nashville” has found its leading man in Chris O’Donnell.

The “NCIS: Los Angeles” actor joins the ABC series as Captain Don Sharpe, who is described as “a rugged fire captain and rodeo rider who runs Nashville’s busiest firehouse with his beloved son,” according to official character description. While Don is described as a “devoted husband and family man,” “he has his secrets,” the description teases.

Other details regarding the plot remain under wraps, though the procedural will follow the lives of first responders in the capital of Tennessee.

O’Donnell is one of the first cast members to board “9-1-1: Nashville,” which landed a series order at ABC in late February. “9-1-1: Nashville,” which marks the third series in the “9-1-1” franchise, hails from 20th Television in association with Ryan Murphy Television, with Ryan Murphy, Tim Minear and Rashad Raisani serving as executive producers and writers.

Brad Falchuk, who...