Book M is the third studio album by Secret Chiefs 3, released on 11 September 2001 by Web of Mimicry.

Our trusty label’s mail-order timed the CD shipment to land on people’s doorsteps right at that fateful moment on Sept 11.

"[2] Founding member Trevor Dunn appeared on only one song, due to scheduling conflicts with the metal supergroup Fantômas in which he also performs.

Blake Butler of AllMusic commended the production and musicianship of Book M, saying "the band proves that they command an amazing grip on their musical reigns, executing flawlessly tight arrangements, even if they are extremely peculiar.

"[3] Sean Murphy of PopMatters called the album "a near-masterpiece and while it’s delightfully weird enough to scare off the amateurs, there is abundant joy to be found within.