HAVE, GET, LET, MAKE + object + infinitive

Have, let and make are followed by an object + bare infinitive:

I'll have her copy the document right away. (I'll ask/tell her to copy the document right away.)
In the end, the terrorists let the hostages go. (The terrorists allowed the hostages to go.)
The teacher made Jack rewrite the composition. (The teacher forced Jack to rewrite the composition.)

Get is followed by a to-infinitive:

Finally, we got a mechanic to repair the elevator.

In the passive, make takes a to-infinitive:

Jack was made to rewrite the composition.

But let takes a bare infinitive:

In the end, the hostages were let go.