since age 5 he had electrified audiences around the world with hit songs like "i want you back". and the world appeared ready to welcome him back. it had been 12 years since jackson's last major performance. the king of pop was poised to regain his throne. >> this is it. this is the final -- this is the final curtain call. >> according to the contract with concert promoters aeg, michael was to perform 50 concerts at the o2 center in london over a nine-month period. >> i'll be performing the songs my fans want to hear. >> but was michael physically up to the challenge? both michael and aeg had a lot on the line. >> it was his comeback. it was his renaissance, his rebirth on stage. after so many years of being out of the spotlight, a lot of people were wondering if he could pull this off.