Researched to Death

"Was it National Old Boyfriends Week, and I'd missed the memo?"
Librarian Jamie Brodie is looking forward to a week of vacation in Oxford, England, his first trip back in seven years. Before he's even packed, though, a couple of complications arise.
The first complication is Jamie's ex, Ethan Williams, who shows up at Jamie's office with his new boyfriend and a request. Ethan's going to Oxford too, and he needs Jamie's help to find a rare 15th century book in the Bodleian Library. When Jamie tells his boyfriend Pete that he and Ethan will be in Oxford at the same time, Pete doesn't react well. To say the least.
The second complication is Pete's ex, Luke Brenner, who shows up at Pete and Jamie's house. He lets Jamie know that he's in town to get Pete back - but Pete doesn't think Luke will try anything.
He's proven spectacularly wrong, in one horrible moment.
Jamie leaves for Oxford, not sure where he stands with Pete, not looking forward to seeing Ethan. When he requests the book that Ethan needs, he learns that it's been missing for three weeks - and the man who likely stole it is dead.
Then two more men die, and Ethan goes missing as well. Is he in danger? Or is he a killer? And what could be in an obscure medieval manuscript that's worth killing for?