Memento Mori

Six people, who seem to have nothing in common, wake up in the same room. They can see a painting on the wall, Memento Mori - 'Remember the death' in Latin. Soon, the six face a dangerous game that may get their lives. Their identities and background information gradually reveal, leading to a case 10 years ago where a young boy was kidnapped and murdered. Who kidnaps the six to uncover the truth behind the horrible death?