Step 1: Understanding the Force on the Wire.
The force on a wire carrying current \( I \) due to the magnetic field from another wire is given by:
\[
F = \frac{\mu_0 I_1 I_2}{2\pi d}
\]
where \( d \) is the distance between the wires. Since the third wire is placed midway between the two wires and anti-parallel to one of the wires, the force on it will be directed towards the wire carrying the larger current (i.e., towards the wire carrying current \( 2I \)).
Step 2: Final Answer.
Thus, the force on the third wire will be towards the wire carrying current \( 2I \).