Siobhan MacDonald was born in Cork in the Republic of Ireland. She studied engineering at University College Galway and pursued a successful career writing for the technology sector in Scotland for ten years, then in France before returning to Ireland.

Growing up in a large Irish family, there was a premium attached to being able to tell a good story. Siobhan's mother taught speech and drama and was a proficient storyteller herself, a talent she encouraged in all her children.

After many years writing short stories and articles, Siobhan published her first novel Twister River in 2016. Siobhan followed this up with her second novel, The Blue Pool. Twisted River won an Earphone AudioFile award in 2016 and The Blue Pool has been a top #10 bestseller in the Australian Kindle chart. Guilty is her first novel for Constable, Little, Brown.

Siobhan lives in Limerick, Ireland with her husband and two sons.