Two years ago Chris Wright made a promise to his daughter Demi at her hospital bedside that he would run the London marathon in her memory. She was dying of cancer.
Doctors initially thought she was pregnant as her tumour emitted similar hormones but she was later diagnosed with a form of terminal colon cancer and died five days later, aged 22.
Demi's parents Chris and Rosalind Wright, from Colchester, want to tell their daughter's story to raise awareness in the hope it could save someone else's life.
Their family and friends have already raised more than £20,000 for Cancer Research UK.
Chris will run the London Marathon on Sunday (22 April) in Demi's memory.