In this World War II action drama, Major Jamie Wilson, Lloyd Bridges hatches an audacious plan to strike at Le Clare, a port held by the Axis that houses the only dry dock capable of servicing their massive battleships. The operation, coded as Operation Mad Dog, would have a destroyer packed with explosives rammed into the outer gate, while Wilson’s commandos unleash havoc across the dock facilities and garrison before the explosive-laden ship detonates.
Opposing him is Royal Navy Captain Owen Franklin, Andrew Keir, whose own son fell during Wilson’s disastrous Dieppe-type raid on the French coast at Le Plagé. Under mounting political pressure, the mission is greenlit even as the naval force allotted to it is slashed: what remains is a minesweeper instead of a destroyer, no escort craft, and only four motor launches for support.
The mission’s naval commander, Lieutenant Commander Donald Kimberly, Mark Eden, is blinded in a training accident while trying to save an injured commando who dies from his injuries. With no viable alternative, Franklin is ordered to replace him, and the two men are thrust into direct conflict as they head toward France. A night-fighter delay tests their resolve, but Franklin surprises Wilson by endorsing a plan he’d proposed weeks earlier: mine the approach to mislead the Germans into thinking the operation is routine.
Across the Channel, the convoy presses on as German coastal batteries open fire to stall them. The minesweeper advances toward the dock gates, and the German defenders become aware of an approaching force—yet the assault continues. The commando storm succeeds, but Wilson is mortally wounded when the minesweeper is struck again, leaving him on the bridge to witness the unfolding chaos.
Inside the port, a fierce running battle rages between the commandos and German troops. Franklin is captured and brought to the German HQ, where Colonel von Horst presides over the stunned garrison. Meanwhile, a German party led by Captain Erich Strasser boards the minesweeper and heads for the smashed bridge. Wilson, barely alive, realizes the detonating circuit has been compromised. With the last of his strength, he seizes the moment, linking the two wires just as Strasser fires, and the detonation shatters the dock gate.
In the German HQ, Franklin’s wary smile gives way to relief as the blast sends tremors through the building, and the commandos storm in to liberate him, killing von Horst and his men. The surviving team pulls away on waiting motor launches, their mission complete as the Axis’s dry dock lies crippled and the broader fight moves forward.
