Watch 999: Killer on the Line? Season HD Full Free on solarmovie.do. Watch 999: Killer on the Line? tv series online free. This series looks at murders that were callously planned and premeditated, with the 999 emergency ca...This series looks at murders that were callously planned and premeditated, with the 999 emergency calls originating from the killers themselves, who concocted elaborate cover-up stories to avoid justice.