Nah, they're good friends and fun to game with. They just made a little misstep and decided to go all in instead of running. One PC had invisibly infiltrated the meeting at the lighthouse in Orithea, and used the Messenger Wind to contact the rest of the group. When the lantern had a mishap, he cast a spell to get people's attentions, smashed out a window to make them think he was running one way, then invisibly ran into the meeting room and grabbed the schematics of the lantern. Bree noticed that and alerted all the guards outside, who tried to find the invisible guy.
The PC jumped onto a carriage, spurred the horses, then jumped off. The guards started shooting at the carriage, as the PC predicted.
The rest of the party, which was hanging back, heard gunshots and came in to help, thinking their ally might be under attack. They figured if he was captured, the jig was up, so they might as well make their move. One grueling battle later, twenty guards were dead, Luc had perished when he provoked an opportunity attack (the fighter assumed, "He's an important NPC. He's got to be high level," then knocked him unconscious and let him bleed out), Ottavia was captured, and Bree managed to feign her death, drink a potion of invisibility, and slip away.
The group interrogated Ottavia, and got a little bit of information out of her, but killing Luc, even accidentally, made her pretty unwilling to cooperate. They knew they couldn't take her back on the train, so two PCs took her out of the city into the malice lands, executed her, then buried her body and kept her head in a bag of holding (Luc's too) so they could try to use magic later. I planned to bring the two back as vengeful spirits in the vault.
The group did have a halfway decent plan -- they rifled through Ottavia's possessions and found papers that let them forge her handwriting, then in Trekhom used a hat of disguise to look like her and had a courier deliver a letter to the lighthouse, which claimed that the meeting was postponed due to trouble in Orithea, and asked that they get a message up the chain of command that they would still rendezvous in Vendricce. The plan was to try to cover the absence of Luc and Ottavia, then still be able to spy on the big meeting.
Unfortunately, Bree had gotten away, and she was able to hop the train west to Cherage and report directly to Sovereign Jierre. So the party was walking into a trap anyway. Still, I expected at least a few of them to escape and survive.
