It was a scene of unspeakable evil when a routine callout turned into Queensland's deadliest police shooting.

Four young police officers were ambushed in the outback town of Wieambilla. Two were executed in cold blood, and an innocent neighbour was also gunned down. Two officers escaped the siege, injured but alive. Dozens of police reinforcements engaged in a six-hour gunfight against three heavily armed cop killers.

An investigation would unearth a dark and twisted web of conspiracy theories and religiously motivated terrorism. How a routine callout spiraled into a bloody massacre will be probed in a coronial inquest.

The Ultimate Sacrifice is the latest podcast from the acclaimed team of 9News presenter Melissa Downes and producer Jessica Lodge, following their multiple award-winning podcast Hannah's Story, and is produced in partnership with 9News and 9Podcasts.

Content Warning: This series contains content that may be distressing for some listeners.