Thomas and Rusty are both trapped at a tunnel and can't go any further until the the heavy snow is cleared away that has fallen. So to pass the time, Rusty tells Thomas the story of how Skarloey was traveling through a ravine when an avalanche came down on him.

The Fat Controller has opened a new mine, and both the normal gauge and narrow gauge railways have tracks to it. An old boulder has had to be moved to make way for the mine, and Rusty is worried about it. Some time later the boulder is shaken loose and falls off the cliff it has been placed on and it chases Rusty down the line! Rusty manages to escape via a siding, but the boulder continues to thunder along! Back at the mine, Percy, with nowhere to run, sees the boulder up ahead, and it's heading straight for him...

Peter Sam is pulling some trucks, but when he has to stop to take on water, they use the opportunity to break away. The trucks are thrilled to be on their own - until they come to the ravine bridge and fall in. Peter Sam is told off and Duncan has great delight in teasing him. Rusty tries to stop this by telling the story of an engine who tried to cross the Old Iron Bridge but never made it to the other side due to loss of control. Duncan thinks this is a load of nonsense and puffs away, so the Driver and Fireman plan a trick to play on him for when they cross the bridge that night...

Toad the brake van is feeling glum as he is always seeing things sliding away from him and would like to go forward for a change. Oliver wants to help but doesn't know how. That afternoon, Oliver is pulling some trucks up Gordon's Hill, with Toad as his brake van. The trucks break away after a coupling snaps and now Toad is at the front of the train going forwards. Unfortunately he is on the Main Line with various possible disasters up ahead!

Mrs Kyndley is upset that her sister, who was coming to visit, isn't able to make it. The Fat Controller decides Mrs Kyndley needs cheering up and asks Harold and James to help out.

Percy is pulling some trucks up a hill when the coupling between him and the first truck breaks. This causes the trucks to break away and roll down the line, and at a tremendous pace at that! Will Percy catch them in time before they cause even more of a disaster?

The Fat Controller, his wife and grandchildren go on holiday, but various incidents keep affecting their plans!

Percy discovers from Mrs. Kyndley that her daughter is to be married "today" but has forgotten about the good luck package. Percy decides to try and help out with the problem.

Oliver has to take the Post Train for the first time, and he gets lost on the way home. But what is it that he has found?

Harold is seen by the engines suspiciously flying around and think he's scouting the area so he can find ways to replace them. Thomas tries to find out the truth, but what does the children's playground have to do with it?

Thomas and Percy discover Old Slow Coach, who is going to be scrapped. They want to save her, but aren't quite sure how. Later, the workmen's hut is burned down and the fire engines have to borrow water from Thomas' and Percy's tanks to put it out. But where will the workmen live now?

Whilst waiting for his fish vans to be loaded up, a crate of fish is accidentally dropped on poor Thomas! On the way to the docks, Thomas notices that the coastal line is damaged, and on his arrival with the "Flying Kipper" trucks which are to be passed on for Henry to pull, Henry teases him about his fishy smell. Then when Henry heads off, the signalman is unaware till too late that he has accidentally switched the train onto the damaged coastal line, which won't be able to take Henry's weight for sure!

The Fat Controller and his grandchildren, Bridget and Stephen, discover an old castle as well as the mine where "the little engines once worked" whilst out on a trip with Toby and Henrietta. The Fat Controller decides to turn sites into tourist attractions, but Toby hears that the mine is haunted...

Stepney is bored, so the Fat Controller agrees to allow him to help out Mavis and Toby at the quarry for the day. He works well, but on the way home gets lost and ends up in the scrapyard, where diesels 'Arry and Bert take him for scrap!

Bill and Ben need some help at the China Clay Pits, so the Fat Controller sends a diesel, Derek, to help them out. But Derek suffers from mechanical failures, "teething troubles", and as expected, this leads to difficulties...

One evening, Henry has to take some trucks to the other end of the line, and everything is fine until he has to travel through a spooky section before a viaduct, of which Henry becomes convinced is haunted after experiencing quite some oddities...

Toby has been sent to check the dam on the river. It has been raining heavily recently and there are worries the dam won't hold. After inspection, the dam starts to break up! Will Toby escape its wrath in time?

Percy has been working very hard recently and feels put upon by this. The trucks find out and try to make him work even harder. Percy then takes them to the mine, but they break away and cause the mine to collapse. Will Percy escape the vicinity in time?

The stations on the Island of Sodor are entering the "Best Dressed Station" competition. Percy agrees to help Maithwaite try and win by delivering fruit and vegetables to decorate the platform. On the way there with his special load, he has an unexpected run-in with a stray ram - however, the hungry creature later becomes Really Useful when some vandals strike at Maithwaite!

George the Steamroller is working around the island and as usual, is causing great problems for the engines. But this time, he just takes things too far. Will he receieve his just desserts?

One morning, a special coach is being prepared to be coupled to Gordon to carry a V.I.P but unfortunately the turntable it is on becomes jammed. After Godon finally receives the coach after the turntable's repair, he puffs off to Kirkronan station to pick up the mystery person. But as he is now late, will he make it on time or will "gremlins" strike again?

James has recieved a new coat of paint and becomes too cocky, even to recognise the dangers trees could cause. However, he learns his lesson when his trucks cause trouble for him during wet weather.

It's Lady Hatt's birthday, and her husband, Sir Topham Hatt, is throwing a party for her. While driving on his way to Kirkronan where the party is being held, he accidentally runs into a large pothole in the road and this leads to all sorts of unexpected difficulties for the poor chap!

Gordon is to take important people to the opening of the new station at Kirkronan, but as he comes near his crew find that they can't stop him, and he's heading for the station wall, and fast...

The engines are working really hard, and the Fat Controller thinks they need some help. He hires 3 lorries to help them, but the lorries are rude to the engines. The engines have the last laugh though when the lorries get into difficulties.

At the docks, Thomas and Percy are working hard, but the new crane, Cranky, thinks little engines are useless - "bugs" he calls them. But that night some rough weather makes a tramper crash into the shed where Gordon, Henry, James and Duck are, trapping them inside. Cranky is then toppled over by the high winds. Who will save them all now?