NCIS: Los Angeles returns tonight after an all-new NCIS.

In the first installment of the year, Nell plays a key role!

When a researcher with the Department of Defense is found dead, Nell must put more than her high IQ to the test when she goes undercover as his replacement. Think she can pull off actual field work? We'll find out!

Meanwhile, Hetty’s ability to lead the team is questioned by the new NCIS Assistant Director, Owen Granger (guest star Miguel Ferrer). Suffice it to say he does not mesh with Callen, Deeks and Sam right off the bat.

The NCIS spinoff certainly has not lacked for internal power struggles this season, with Hetty's fate, and authority, appearing precarious on more than one occasion. But never count the diminutive shot-caller out.

Watch the promo for "The Watchers" below:

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.