The episode is written by Steven D. Binder and directed by Arvin Brown, and was seen by 19.30 million viewers.
The cellphone belongs to an Eddie Macklin but the team keep hitting dead ends with the evidence.
However, the case takes an unexpected turn when Gibbs and Fornell discover that "Eddie Macklin" is the alias of Secret Service Special Agent Edward McKenzie and that NCIS had stumbled on a highly classified six-month-long undercover operation.
[3] "Devil's Triad" was seen by 19.30 million live viewers at its December 10, 2013 broadcast, with a 2.9/8 share among adults aged 18 to 49.
Douglas Wolfe from TV Fanatic gave the episode 4.2/5 and stated that "The idea of murderous clowns has got to be everyone's favorite nightmare.