Jon Amiel will direct the project, named after the code used by Armed Forces Radio in 1975 to alert citizens to evacuate the former South Vietnamese stronghold.
William M Akers' screenplay focuses on several characters and their struggle to flee the country as victorious North Vietnamese troops prepared to storm the barricades.
Echo Lake's Doug Mankoff, Mike Marcus and Andy Spaulding are producing alongside Rob Cowan. Echo Lake developed the project with Amiel and brought it in to Overture.
'We've wanted to bring this powerful story to the screen since Chris and I started Overture Films,' Overture's chief operating officer Danny Rosett said. 'It fits within our mission at Overture: to give artists the tools and the freedom to make entertaining, quality films.
'With Doug Mankoff and everyone at Echo Lake, we found a company equally passionate about that philosophy.'
'105 Degrees is a fresh look at this key moment in our history' Echo Lake president Mankoff said. 'The script features an ensemble of amazing roles and Jon Amiel brings terrific vision to the material.
'Chris [McGurk, Overture chief executive officer] and Danny have exhibited great taste in making important films such as Hotel Rwanda, and so we are especially pleased to be making this film with them.'
Overture plans to release eight to 12 films a year and made its first acquisition back in January with the Charlize Theron-starrer Ferris Wheel.