Gertie was acompanion of theTwelfth Doctor.

One of Gertie's adventures took place onMars, during its earlier stages when it had water and thriving plant life. She explained to her grandsonCharlie Baker that it was peaceful and quiet, until something interrupted them.

Once she encountered aGestalt Creature which attempted to superheat the planet's surface and destroy all life.

Another time, the Doctor took her to the past to see apyramid, yet they were attacked and chased by amummy.

In1986, the Doctor dropped her off onEarth and told her he'd be back at26 September, but he didn't specify on which year he would return. She waited 30 years until2016, when the Doctor arrived withClara Oswald on aTime dragon. He then took Gertie and Charlie on an adventure to Mars. (COMIC:Super Gran)