It's been seven years since British teen Shamima Begum, then 15 years old, entered Syria with two school friends to join ISIS.

One of Begum's friends has since gone missing, and the other was reportedly killed in an airstrike on Raqqa. Begum herself disappeared for years before encountering a journalist in al-Hawl prison camp in 2019, begging to return to the U.K. for the safety of her child, who subsequently died.

Now, the BBC says the man who smuggled the girls into Syria was actually a double agent, providing information to Canadian intelligence as he trafficked for ISIS. A new book by U.K.-based writer Richard Kerbaj also accuses Canada of asking British officials to help cover up the connection.

BBC journalist Joshua Baker has been interviewing Begum for the upcoming podcast, I'm Not A Monster: The Shamima Begum Story. Today, what he's learned about Begum's journey and Canada's involvement from a dossier on her alleged smuggler.