Infiltrate

Infiltrate is a song included in the Halo 3: Original Soundtrack. It plays during the level Sierra 117, and includes the tracks Infiltrate and Move On.

Infiltrate plays during the section with all the Jackal Snipers, up until the beginning of the Quid Pro Quo section of the level. It starts with a low strings note, with drums playing background. High strings play and hold a note, but drums continue to play melody. The song picks up the pace, and louder drums join in. Infiltrate runs for about 1:48.

In Move On, which plays near the end of the mission when Hocus destroys the two Phantoms, strings begin to play the melody, which is in a minor key but has a hint of major in it. Choir also joins in, but strings and drums still keep the melody, which alternates between major and minor. This melody continues until the end. Move On runs for about 1:58.

Overall, it runs for 3:50.

Trivia

 * When the bass begins followed by the three percussive sounds, seven such percussion sets follow before the percussion suddenly becomes high-pitched and then returns to normal. This is another 7 reference. Strangely enough, it never happens again in the song.