Richard's friends almost inevitably started to plot together. The two Hollands (formerly Exeter and Surrey but now busted down to Huntingdon and Kent respectively) and Salisbury were definitely involved. Thomas Despenser was almost certainly involved, although there is just a small chance that he wasn't as he doesn't get much of a mention in most accounts. As for his brother-in-law, Edward of York, now Earl of Rutland again, if he was involved (and it's not absolutely certain that he was) he betrayed the conspirators.
Other people involved included Lord Lumley (interestingly a retainer of the Earl of Northumberland!) the Abbot of Westminster, the Bishop of Carlisle and Sir Thomas Blount.
Henry was planning to spend Christmas at Windsor. Most of his friends had gone home, especially the big batallions from the North, so he would be there with his household and maybe the odd close friend - though none are mentioned so it was possibly a bit quiet chez Bolingbroke. The basic idea of the conspiracy was to show up mob-handed at Windsor for a proposed tournament, bump off Henry (and possibly his sons) and make Richard king again. Various subsidiary risings were organised, notably one in Cheshire, and Richard Maudelyn, the king's double and likely cousin, was recruited to play the part of Richard until they could get their mitts on the genuine article. (He was locked up in Pontefract Castle with the grim Sir Thomas Swynford, but they probably didn't know it.)
There are three versions of how the plot was betrayed:
1. Elizabeth of Lancaster (Huntingdon/Exeter's wife) told her brother Henry.
2. One of the people involved told a prostitute, who 'peached them.
3. Edward of York bottled it at the last minute and told his father, who told Henry.
It is certain that Henry got his warning very late, and got out of Windsor, slipping through the rebel lines back to London, where he quickly raised an army of supporters. Shortly after the rebels took Windsor, and probably did a fair bit of jumping up and down in their armour when they realised all had gone to pot.
Edward of York meanwhile was leading the van of Henry's forces against men who had been his friends until maybe hours earlier! Some accounts have him parleying with them, but it's certain that they fought him at Maidenhead Bridge, and held him off until after dark.
Thomas Holland and maybe others visited Queen Isabelle who was lodged at Sonning, and some accounts have her leaving with them - if she did she must have soon parted again, as the rebels, hopelessly outnumbered, were in flight. Plan B seems to have been to get to Despenser's Glamorgan. John Holland (Exeter/Huntingdon) had been left behind to raise Richard's supporters in London. Having failed miserably he fled to Essex where he was eventually 'executed' - murdered by a mob in fact.
The others rested at Cirencester, and found themselved assailed by a mob that had been prompted by one of Henry's agents. Thomas Holland (Kent/Surrey) and Salisbury was captured, while Thomas Despenser escaped by legging it over the roofs. At this point someone, accidently or on purpose, set the town on fire.
Holland and Salisbury were taken into custody by Lord Berkeley, who had conveniently arrived on the scene, but it appears that the townsfolk were so miffed by the damage (none of them were insured after all!) that they insisted on taking the pair from Berkeley and beheading them on the spot.
Thomas Despenser got as far as Cardiff, but there made the mistake of getting onto a ship. He and his men were overpowered and taken to Bristol, where there was another piece of lynch justice. Various lesser men were tried at Oxford, and there were a number of full-blown official executions with the full process of hanging, drawing and quartering. A lucky minority received pardons, including one fellow who had saved Bolingbroke's life during the Peasant Revolt of 1381.
The consequence of this was that Henry IV issued an order for Richard II to be murdered. He probably thought that would put an end to any future plots against him. He was seriously mistaken.