"They were born out of the same cosmic egg," says one of the interviewees in "Grateful Dawg", explaining the relationship between The Grateful Dead's lead guitarist Jerry Garcia and mandolinist David Grisman.

Judging by this warm and gentle documentary about the legendary Amercian Band, that's exactly right. Garcia and Grisman - two larger than life, bearded music nuts - seem to be the perfect partnership.

Meeting in the early 60s through their shared love of bluegrass king Bill Monroe, these two musicians became regular collaborators.

An argument over business affairs split them up in the mid 70s but they reunited in 1990. They continued to jam and record all kinds of folk tunes and acoustic numbers until Garcia's death in 1995.

Paying tribute to her father's collaboration with Garcia, Gillian Grisman's documentary is, as you'd expect from a family member, an intimate affair.

It's full of insight into the working relationship of these two master musicians. Splicing in talking heads with concert footage, "Grateful Dawg" is a fascinating history of two of America's foremost musicologists and their passion for anything with a musical scale.

Under strict instructions from her father, Gillian Grisman gives the music centre stage. She ensures all the featured tracks are played in their entirety and even filmed several sessions featuring unreleased live audio tracks.

Yet "Grateful Dawg" is more than just a documentary about music. It's also a story of friendship and professionalism - a tale of two soul mates.

Watching these two aging hippies hanging out together, discussing banjos and mandolins, it's hard not to feel inspired by their sheer passion and enthusiasm.