Peril
From Halopedia, the Halo wiki
Peril is a piece of music featured in Halo 2, and is present as track three on Volume 1 of the Halo 2 Soundtrack. The song's length is 2:47
The music is centered around use of strings, and provides a tense atmosphere during sporadic combat sequences.
The song is heard around the start of Delta Halo after the Master Chief has cleared the initial defenses around the landing zone and immediately prior to the arrival of the Phantoms. It is later heard as the Chief makes his way through the 'outdoor' areas of High Charity in the level Gravemind.
This song also appeared in 'Top Gear' on Sunday 23rd December 2007 on BBC 2 at 8pm. It was featured while James May was reviewing the Jaguar XF