The Bolivian expedition’s bat attacks transform a troubled field mission into a lethal crisis, killing members of the party and soldiers, destroying vital supplies, and leaving the survivors to decide whether to evacuate or continue. Recounted in a letter addressed to Paul, the assault also gives its unnamed writer a new clarity about the mission and about the life he would return to.

Causes and Background

The letter places the expedition less than five kilometers from its intended grave site, but the planned extraction is already in doubt: too many members of the party are sick or dead. The first attack comes two nights before the letter is written, a few hours after sunset, while most of the group is outside its tents doing evening chores. The writer, away from camp upriver in search of a GPS signal, hears the shouts and gunfire and returns after the swarm has moved downstream.

The attack is striking partly because its timing and direction make it seem deliberate. The writer wonders whether the bats had been scouting the group and waiting for an opportune moment, though the letter does not establish that they were. This remains an eyewitness account under pressure: the narrator describes what he saw and heard, but can only speculate about the swarm’s behavior and the illness that follows.

The Attacks and Their Immediate Toll

The first assault kills four people, including Claudia. She tries to reach the river, apparently hoping it might help her escape the bats, but does not make it. Six other people are bitten or scratched. The writer describes their condition as resembling an unusually rapid form of Bolivian hemorrhagic fever, but emphasizes that its cause is uncertain: the expedition has contacted the CDC, yet without tissue analysis the diagnosis remains guesswork. Tim is among the most severely affected after trying to pull the bats away from Claudia, and the narrator doubts he will survive the night.

The bats return the following night despite the soldiers’ defensive perimeter. The writer estimates that they arrive by the hundreds of thousands, in a swarm large enough to blot out the stars. Three soldiers and Cole are killed. Cole is taken off his feet by the swarm, and so little remains that the survivors can barely bury him. The scale of the losses makes the danger more than an isolated attack: the perimeter has not protected the camp, and the expedition has lost people on consecutive nights.

Damage, Evacuation, and the Decision to Stay

On the night of the letter, the sky is quiet, and the expedition has built a line of fire around the camp that seems to be keeping the bats away. The pause offers some immediate protection, but the survivors are badly shaken and their resources have been reduced. During the previous night’s attack, a grenade belt goes into the fire. The resulting explosion kills a soldier and destroys the generator along with most of the supply tent’s contents. The letter does not explain how the belt reached the fire; it records the loss as an unresolved consequence of the chaos.

Despite the destruction, the group retains satellite communications and enough battery power to call for evacuation. The survivors are deciding what to do, and the narrator acknowledges that leaving may be the sensible course. His hesitation is personal as well as practical: he recognizes that his wife, Liz, is dead and that he has been maintaining the hope that she might somehow return. He recalls ordinary images of life with her, including tea and walks by the Charles in falling snow, and understands that this imagined reunion will not happen. That recognition changes how he sees the risks of staying. He says the preceding days have clarified the stakes, that he does not regret being there, and that he may continue alone if necessary.

The Letter’s Function and Significance

Addressed to Paul in case the writer does not return, the letter makes the disaster both a field report and a personal reckoning. Its sequence is precise: an account of the first attack, the worsening illness and deaths, the second swarm, the loss of equipment, and finally the decision still facing the survivors. Against these concrete dangers, the narrator places the death of Liz and the realization that there is no homecoming waiting for him. The assault does not resolve the expedition’s objective; it leaves the group close to the grave site but uncertain whether it can proceed.

The closing passage redefines the relationship between the writer and Paul. He calls Paul more than a friend, a brother, and reflects on the distance between their familiar lives and the riverbank in the Bolivian jungle where he writes. He describes himself as having entered a new era of life, shaped by the strange and dark passages that have brought him there. The letter ends without revealing whether he evacuates or presses on, preserving the immediate uncertainty that the attacks have created.