Gabrielle Union has signed on to co-star the upcoming Lifetime movie The Vow, according to Variety

The telepic is in development at Sony Pictures TV and is based on the 2005 novel by Denene Millner, Angela Burt-Murray and Mitzi Miller about three women who attend a wedding and all decide to be engaged within the next year.

Nzingha Stewart is adapting The Vow for television.