Early in the spring, Tom Faggus comes to discuss setting a wedding date, and meets Lora for the first time. He is sure that he's seen her before- when she was a child- but cannot remember the occasion. He also tells them that the necklace which Lorna got back from Sir Ensor is not glass beads: it is made of 25 rare, pure diamonds and is worth a king's ransom. As a reformed highwayman, Tom knows quality jewels when he sees them. They assume that the Doones must have stolen the necklace from one of their many victims.
After Tom leaves, Jeremy Stickles arrives with bad news. He cannot get any government troops assigned to him to move against the Doones for some time yet. He recommends that John start setting guards around the farm and keep watch at night. He also suggests that John ride over to the village where Stickles' own men, few though they be, are stationed and tell them to come to the farm. John does so, but uneasy about being away, rides back home ahead of them. He arrives to find the women badly shaken. Earlier, while in the farmyard, Lorna had looked up to find Carver leering at her from across the flooded brook. He pointed a gun at her and shouted that, if she didn't come back, she and everyone else on the farm would be killed. What a charmer. Lorna offers to go back to save all of them, but is of course not allowed to do so.
More men arrive to defend Plover's Barrow, and it is doubtful that the Doones will attack again while it would be a fair fight. John takes advantage of the temporary peace to ride to Dulverton to visit Uncle Reuben. Ruth greets him warmly, but Ben is not there. Ruth says that her grandfather has been acting oddly for the last six months, coming and going at odd times and not taking interest in the business. While waiting for Ben to show up, John tells Ruth about Lorna. In love with John herself, and having harboured some hope in that regard due to his mother's meddling, Ruth is devastated by this news but tries to hide it and wishes him well.
John waits as long as he can but Reuben never shows up, so he heads back home. He arrives to find Counsellor Doone at the farm. He is laying on the charm, but has really come to try to cause trouble between John and Lorna by telling them that each of their fathers was killed by the other. Lorna says that she doesn't believe him, because all the Doones are liars, and that even if it's true, it won't change how she and John feel. Incredibly, instead of kicking him out the door, or better yet, calling the soldiers to arrest him, they let him spend the night. He repays this hospitality by tricking Annie into showing him Lorna's necklace, which he of course steals.
There is no time to dwell on this, however, because Jeremy has raised a force of fighting men and together with his troops and some of the local civilians, is ready to attack Doone Valley. John goes with them and they march on the Doones. Unfortunately, the battle ends in disaster. The civilians are untrained, and the soldiers who are from two separate regiments regard each other as rivals and don't work together. On the other hand, the Doones have trained in warfare since childhood and fight as one. It is a complete rout, and many are killed. Jeremy Stickles is badly injured, and John takes him back to the farm where he spends a long time healing, and is never completely well again.