The Backstreet Boys originally built up their massive fan base in Canada and Europe; it wasn't until the 1997 release of second studio album Backstreet's Back that they grabbed the ears of millions of teenage girls in the U.S with their intensely sweet, danceable pop. Just when the band's popularity seemed to be peaking, things began to unravel. In July 2001, a tour was put on hold when A.J. McLean checked into rehab. McLean had barely rejoined the tour when tragedy struck: a close associate of the band died on one of the hijacked planes on September 11. The group soon regained its strength when Greatest Hits Chapter 1 was released. The album featured the single "Drowning," which once again put the Backstreet Boys back on the pop charts. But the next year saw Nick Carter getting arrested and the band filing a multimillion-dollar breach of contract lawsuit against their record label. It didn't come as much of a surprise, then, when the Backstreet Boys announced in early 2003 that each member would focus on their own projects. But it wasn't long before they returned as a group to the spotlight with 2005's Never Gone. Two years later, they came out with Unbreakable.