Into the Cauldron brings together two of the most innovative mandolin players on the bluegrass fringe. Mike Marshall is a veteran of the progressive “pyschograss” movement, while Chris Thile has split time between the cheery pop of the platinum-selling band, Nickel Creek, and some challenging and less accessible solo fusion work. Marshall and Thile are the only two musicians on the record, so there are times when one’s ears become weary of their high-pitched rapid fire plucking. To their credit, they do a fine job of mixing up the tempo and mood to rescue the album from sameness. Their playing throughout is gorgeous, but it is their arrangements that are the true strength of the album. An interpretation of Charlie Parker’s bebop classic “Scrapple From the Apple” is particularly fine as Thile plays Miles Davis to Marshall’s Bird with precision and fire. The joy of listening to these two play is in their uncanny feel for each other, one dancing around the melody while the other sits back strumming an intricate rhythm. In fact, it is oftentimes the rhythm parts that are the most intriguing, as in the breezy Brazilian-accented “Desvairada,” and Marshall’s use of the mandocello on the Nashvillian baroque excursion of J.S. Bach’s “Goldberg Variations (Var. 1).” Their original compositions are a mixed bag, but the charming newgrass opener “Harvest Time” will remind many of the writing style of Béla Fleck, while the thick meaty power chords of “What a Blast!” will challenge any who think the mandolin is not designed for rock ‘n’ roll ears. Into the Cauldron may be too frantic for many casual listeners, but anyone with an affinity for the guitar’s precocious little brother will be thrilled with this mandolin explosion.