What was believed to be for some time, the final book in the Railway Series, and the last to be published before the death of the Reverend Awdry.  The book follows the adventures of the Skarloey Engines, and introduces us to their new Number 7 - Ivo Hugh.  It also lets us know what happened to Peter Sam when he was spared to go and help out on the Talyllyn Railway in Wales.  There was plans for a 41st book in 1998, but new publishers Egmont and their new formatting of the classic books scuppered these plans completely.  However, the series was not dead, just sleeping... and there is now hope that one day Ivo Hugh's personality will be developed properly!

Speedkiller

Rusty is given the slow job of putting weedkiller on the line, a job which he very much dislikes.  At holiday weekend, a huge turnout of passengers arrive and Rheneas is scheduled to take their train for them.
Rheneas has problems with the train when he has to pass some hedgecutters carefully, and henceforth cannot get a good run at a steep part of the line.  To make matters worse, Rheneas can't get a good grip of the rails either because of Rusty's weedkiller, which Rheneas denounces as being "Speedkiller".  Rheneas' crew lay sand on the line to keep Rheneas's wheels from slipping further and he carries on to the top station with bravery and determination.

Sir Handel's Plan

Sir Handel is jealous of Peter Sam being sent to Wales, and when Peter Sam is allowed time to rest following his return, this makes Sir Handel even more furious.  When he thinks he sees Peter Sam grinning at him near the sheds, Sir Handel hits a rough rail-joint and deliberately knocks his firebars out of place and his fire falls out.
Peter Sam pushes Sir Handel into the shed again and takes his next train for him.  But while Sir Handel thinks he's been clever, as the days pass and no-one comes to mend him, he feels more and more foolish, and more and more alone as he sits and waits. 
But when the Thin Controller comes to see him and see how bad he feels, Sir Handel meekly explains the situation.  The Thin Controller grants Sir Handel the chance to be mended again, provided he behaves himself.  Sir Handel is given a new set of firebars later that day, but no-one told him that they were only delivered that morning!
 
Dirty Water

Peter Sam tells Kathy and Lizzie, two daughters of volunteers from the Talyllyn Railway, all about his time there, and remarks about the cleanliness of the engines who work there, and remembers the time when he took ill and needed a lot of cleaning!
Peter Sam explains that they use something special in the water on the Talyllyn to make it nice, but on this particular day, Peter Sam found the water to taste awful.  Then, when Peter Sam's driver lets water into the boiler, he begins to suffer boiler ache, and finally as he leaves the station, a column of filthy white water sprays out of his funnel. 
Peter Sam was put onto the spare line for the visitors to see him, and later finds out that someone put too much special stuff in the water tower, hence the fact it was bad.  Then he explains that the fireman puts a special pill in the tank when he has a drink!

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I Name This Engine

The new engine is finally ready, but, no-one knows what he's going to be called, and the Thin Controller is remaining tight-lipped about the name.  Even Mr Hugh, the Chief Engineer didn't know what the name was going to be, and that it will be painted on at the last minute.
Skarloey is chosen to pull the train on the ceremony day and to take the Thin Controller and the special guests to the Bottom Station.  As he is setting out on the return journey from Mr Hugh's house, he notices something dashing across the line in front of him.  The Fireman jumps down and discovers a Mother pig and her seven piglets lying in the long grass beside the line.  The Thin Controller, Mr Hugh and the guests join in the pig chase until they're all caught, and Skarloey can carry on.
Skarloey arrives in later than expected for the naming ceremony and Mr Hugh is asked to do the grand unveiling.  When he does, he gets a very welcome surprise when he discovers that the engine is being named in his honour as "Ivo Hugh".