Martine was born in Taber, Alberta, in 1953 to James and Mary Webster. Because her father was in the military, she grew up in various towns and cities across Canada. She moved to Calgary in 1974, married soon after, and over the next eleven years gave birth to six children: Sterling, Sarah, Rachel, Russell, Candace and Derek.

In 1990, as a single parent, Martine attended the University of Calgary and studied Honours English. The Dragon's Tapestry, her first book for young people, was published by Red Deer Press (RDP) in 1992. The Prism Moon (RDP) came out a year later. She began The Taker's Key, the third book in the fantasy trilogy, for her Honours thesis.

Martine remarried in 1995 to Greg Leavitt, and graduated in 1996, first class honours. The Taker's Key (RDP) was published in 1998. She worked for a year, and then quit to have her seventh child, a son named Dallas. She wrote the first draft of The Dollmage (RDP) during her lunch hours at work. It was published in 2001.

Tom Finder was published by Red Deer Press in spring of 2003, the same year she graduated from Vermont College with a Master of Fine Arts degree. She studied under such writers as Carolyn Coman, Brock Cole, Jane Resh Thomas, and M. T. Anderson. Heck Superhero, her creative thesis, was published by Front Street Books in 2004.

For the past four years she has worked as an editor in the marketing department of SMART Technologies, but in January she will be leaving to join the faculty at Vermont College teaching creative writing. In her free time, she likes to hang out with her six grandchildren and serve in her church.