A Mystery Bet takes the guess work out of picking a Trifecta and is generated by the betting agency’s computer.
The computer system will randomly select three runners and if they fill the placings you win the Trifecta.
$3 MYSTERY BET
The three selections in the $3 Mystery Bet can finish in any order just like a Box Trifecta, however the return will only pay half of the Trifecta dividend (0.50 x $1Div).
Mystery Bet Slip example from Sportsbet
$1 MYSTERY BET
The $1 Mystery Bet will pay the full dividend, however the runners must finish 1st, 2nd and 3rd in the correct order.
WHERE TO PLACE A MYSTERY BET
You can place Exacta bets with most bookmakers such as Sportsbet, Ladbrokes and Luxbet, while some bookmakers also offer fixed odds Exacta bets.
If your selection is declared a non-runner or is scratched after you have placed your bet, your money will be refunded on that selection.