Depending on the level of magical resources available to the party, and the number of hostages, there are a LOT of potential options for hostage rescue.

A point-blank Fireball or equivalent centered on the hostage followed by a Revivify is an interesting option, though it becomes very costly and difficult to pull off if multiple hostages have been taken.

A Silent Dominate Person/Finger of Death/Disintegrate (Listed in the order that I, personally, would use them) cast from stealth can remove the hostage taker without them even getting the chance to roll initiative. (At least, in the case of Silenced Dominate Person, because the first indication that something has gone wrong would also neutralize the hostage taker if they failed their save. You could argue with Finger of Death and Disintegrate that the hostage taker could conceivably execute their hostage before the ray reaches them, but after it is fired.)

If the party is REALLY high level, the travel option of Wish could be used to rescue the hostage while standing on the other side of the world. No chance of failure (but a high XP cost, of course.)

Even low level parties have some effective magical options-Benign Transposition (Does that exist in Pathfinder?) could be used to replace the tied, vulnerable hostage with an 7-foot tall, infuriated half-orc with a very big axe. Sleep, especially if you have a way of making it Silent, can be cast from stealth to neutralize the hostage taker. Color Spray can also be used as an AoE option- even if you hit the hostage, he'll be fine in a few minutes. Hell, Daze is a cantrip, and it would drop the hostage taker long enough to make executing the hostages impossible.