Hercules The Really Useful Tug is a TUGS parody of the Thomas The Tank Engine And Friends episode "Edward The Really Useful Engine".
One day, Big Mac is talking about Hercules being retired. Sunshine says Hercules doesn't have tires, and Ten Cents corrects him by saying retired meant taken out of service. Big Mac decided that he shouldn't be retired a moment too soon, and Warrior and Top Hat agreed.
Later, Sunshine tells Captain Star what Big Mac had said, and Captain Star said he'd handle it. He called Hercules to the star dock to put a plan he had into action. He told Hercules that the new quarry canal is complete and he wants him to teach Sea Rogue how to work it properly. When asked about the other work, Captain Star said Grampus would handle it.
When the other tugs heard about Grampus helping them, they were pleased. Warrior said that Grampus is very reliable, but Big Mac says it makes no difference to him and that he doesn't need any help.
Hercules enjoyed working with Sea Rogue on the quarry canal. But Grampus was not happy, because The Shrimpers were playing their silly games. They hold him back and keep him from moving. Big Mac then shows up with a barge of lumber and tries to move Grampus and the Shrimpers, but they don't budge. Hercules is told about this and comes to the rescue. He pulls Big Mac, Grampus, and The Shrimpers out of the shipping lanes and into the harbor. Big Mac embarrassingly made his way to the star dock, where Captain Star spoke severely to him. He tells him that after what Hercules did, he proved that he is responsible, reliable and very helpful.
The next day, Big Mac apologized to Hercules and said that he really is really useful, and Hercules said it was good to be back. Captain Star's plan had worked and there was no more talk of Hercules retiring.