Martin Scorsese's 2006 hit The Departed continues in the legendary director's tradition of engrossing crime stories. The Oscar-winner's resume is well-documented, with highlights like Goodfellas and Casino among his many fan favorites. The Departed marked Scorsese's return to gritty, urban storytelling after forays into historical epics, and with a cast that includes Leonardo DiCaprio, Jack Nicholson, Matt Damon, Alec Baldwin, Martin Sheen and Mark Wahlberg, it's no mystery why the movie was both critically acclaimed and a box office smash. 

One aspect of Scorsese's filmmaking that's always been praised is his use of classic popular music on his soundtracks. His movies incorporate songs from major artists in a way that would influence subsequent filmmakers (think Quentin Tarantino) and also highlighted Scorsese's affinity for classic rock, blues, R&B, doo-wop and 60s pop. But in The Departed, Scorsese showed that he wasn't out of tune with Hip-Hop; using one of the game's most revered MCs in one of the movie's early scenes. 

Nas was riding a resurgent wave by 2006. After some poorly-received albums at the tail end of the 1990s, the Queens legend had come roaring back with his fifth album, Stillmatic, in 2001. He followed it with the acclaimed God's Son a year later, and alongside his highly-publicized feud with rap rival Jay-Z and marriage to R&B chanteuse Kelis, Nas was at a peak. 

In 2004, Nas released the ambitious double album Street's Disciple. One of the album's most celebrated tracks was the stellar Salaam Remi-produced "Thief's Theme," a sinister ode to those who rob in the night, with Nas rhyming over a flip of The Incredible Bongo Band's "In-A-Gadda-Da-Vida," originally recorded by Iron Butterfly. 

"This was the first time that Nas put out a summer," Remi told Soul Culture in 2010. "All of his albums kept coming out...December...a couple of weeks before Christmas."

"Even when Nas was making Stillmatic and 'Ether,' he's like 'Yeah this is that winter beef,'" he explained. "He was like the beat sounded like the winter."

With this particular track, Nas and Remi wanted it to evoke the warmer months.

"So on 'Thief's Theme,' I intended for it to sound like the summer of 2004," Remi shared. "'Last drink from the water drops,' and things he says on the record are directly about being hot. The Peter Tosh references, and everything else. The record was meant to come out in the summer."

"Nobody said 'that record is crazy.' Like, we didn't get that feedback. We got 'uh-oh' what is he doing?"

In The Departed, Martin Scorsese's injects "Thief's Theme" into a scene right after undercover cop Billy Costigan (DiCaprio) teams with his unknowing cousin Sean (Kevin Corrigan) to deal drugs to some Puerto Rican hustlers in their neighborhood. The song undercuts Billy's double-sided nature and Nas makes lyrical reference to John Lennon, who Frank Costello (Jack Nicholson) would also mention later in the movie. 

The song's dark mood both adequately carries the tension of the scene and gives musical weight to the drama between Billy and Sean; Billy isn't a "thief" but he's shady in dealing with his cousin under false pretenses. "Thief's Theme" wouldn't appear on the movie's official soundtrack, but it makes for one of the standout moments in The Departed. 

Nas, like many rappers of his generation, has always had an affinity for gangster epics, and Scorsese looms large. The rapper's 1996 video for his hit "Street Dreams" is a lengthy homage to Scorsese's Casino his line "the Good F-E-L-L-A, verbal AK spray" is one of his most memorable. 

Street's Disciple would be another hit album for Nas and his final before departing longtime label Columbia. His feud with Jay-Z would eventually subside in 2005, with the two Hip-Hop stars sharing the stage at Hot 97's Summer Jam. And in 2006, Nas would sign with Def Jam Recordings, which had named Jay-Z president. In 2006, Nas would release Hip-Hop Is Dead on the label. 

Fans know that Nas would revisit "In-a-Gadda-Da-Vida" with "Hip-Hop Is Dead" two years later. On that song, the classic rock staple is the backdrop as Nas raps about Hip-Hop's creative demise.