A metamorphosis is under way. A face, seemingly made of candle wax, takes shape beneath a flickering flame. It is Annie Lennox, provocative singer of Eurythmics, the British pop duo. Then, the video for Eurythmics’ latest single, “Missionary Man,” turns more sinister, with a scene in which a dark figure — Dave Stewart, the duo’s other half—is seen cooking potions in a laboratory. The video cuts back to Lennox’s face, now helplessly harnessed to a set of mechanical devices— communicating a strong message of struggle against others’ attempts at control. For Lennox and Stewart, veterans of contractual disputes with record and management companies, that message has special resonance. The pair ha...