The Decagon House Murders

Seven students, members of their university's mystery club, decide to spend a week-long vacation on Tsunojima Island off the coast of Japan. Six months earlier, the owner of the island was brutally murdered alongside his wife and housekeepers, and the case remains unsolved. Soon after their arrival they begin to suspect that one of their number is intending to kill them one at a time, but who? (Source: Wikipedia)