It's a masterpiece that is mainly instrumental music and is structured like a concept album.
The fourth album released in 1972. The fusion style became stronger from this album, and seven of the ten songs were instrumental. It reached number eight on the Billboard 200 and number six on the R&B chart.
This album was produced after original members Dave Brown and Michael Carabello left the band. Gregg Rolie (keyboards) and Neal Schon (guitar) left the band after this album and formed Journey.
