By early 1971, with Christine McVie becoming an official member of the band, Fleetwood and the group boarded a plane to San Francisco. Spencer, fearful following the recent 1971 San Fernando earthquake, reluctantly boarded the plane. He left the hotel abruptly one afternoon and disappeared. He was found several days later to have joined Family International, then known as Children of God, a religious group. Once more, Fleetwood attempted to mediate; however, Spencer would not return. Bob Welch would become their next member. Their next album, "Future Games", was released later that year. "Bare Trees" came a year later, in 1972. During the subsequent tours to promote the latter, Fleetwood once more adopted the role of mediator. Kirwan's self-destructive personality and problems with alcohol culminated in a refusal to go on stage before one concert; Fleetwood himself made the decision to fire the band member. Furthermore, there were early signs of strife in the marriage of John and Christine McVie. Fleetwood again stepped in to mediate between the two members, talking Christine out of a decision to leave the group. The band added guitarist Bob Weston and vocalist Dave Walker, formerly of Savoy Brown and the Idle Race. The resulting turmoil, however, negatively affected their next album, "Penguin", released in 1973 to poor reviews. Walker was subsequently asked to leave the group, and the next album "Mystery to Me" was received more warmly.