You had the misfortune of falling prey to a trap. A seemingly innocent unattended campfire. When you investigated you were set upon by 2 revenant archers, 2 zombie brutes and 5 skeletal minions. The archers used the terrain to their advantage by attacking at long range as the brutes held you in position.
Two crucial events occured, Inara was hit by a powerful attack that dazed her (SE) and she promptly failed her saves for several rounds. This allowed the monsters to switch locations that took them out of Inara's line of site while a group of skeleton engaged her.
The second crucial event occurred as the party was finishing destroying the undead, it was an intense combat with dailies, healing and second winds being used by all, but the advantage was clearly in the PC's favour. Only the archers remained when one of them felled Solaria with a devastating arrow shot. Ralts quickly killed this archer, but the final archer decided to run away. With Solaria dying, and Inara unable to assist her, the other party members opted to give chase to final archer, before eventually returning to help Solaria.