The publication of this book could hardly be more timely. At a moment when biological threats are once again moving from the margins of security planning to the forefront of strategic concern, Annie Jacobsen has produced a compelling and deeply unsettling examination of how biological warfare could shape the next global catastrophe.

Following the success of Nuclear War, Jacobsen turns her attention to another area of existential risk. As before, she explores the most extreme scenario imaginable. Some may criticise this approach as alarmist, but by examining the absolute worst case, she forces readers to confront uncomfortable questions about preparedness, resilience and political decision-­making. If reality falls short of her scenario, we should regard ourselves as fortunate rather than feel reassured.

Jacobsen’s hypothetical scenario centres on a genetically modified strain of plague, one of history’s most devastating diseases. She takes her inspiration from a real explosion at Russia’s Vector laboratory in Siberia on 16 September 2019, for which officials blamed a faulty gas tank, and which caused a fire. There were no biohazardous substances in the laboratory that caught fire in 2019. Jacobsen asks what might have happened if there had been.

Using an impressive body of evidence and the expert testimony of over fifty interviewees, she constructs a minute-by-minute, hour-by-hour, day-by-day narrative that feels remarkably authentic. She clearly understands not only the science of the Chemical, Biological, Radiological and Nuclear (CBRN) field but also the institutions, cultures and vulnerabilities surrounding modern biodefence. Much of what she describes is technically credible.

The fictional storyline immediately brings to mind I Am Pilgrim by Terry Hayes, one of the finest thrillers ever written on biological terrorism. Like that novel, Jacobsen’s story is rooted firmly enough in scientific and operational reality to make it genuinely unsettling. The difference today is that COVID-19 fundamentally altered our understanding of biological risk. Before the pandemic, many professionals regarded biological weapons as relatively unattractive instruments of war because their effects were often slow and unpredictable. Covid changed that calculation entirely. A pathogen with comparatively modest lethality brought the global economy to a standstill and overwhelmed health systems across continents. Jacobsen asks the obvious next question: what if a pathogen were deliberately engineered to be vastly more lethal?

Hers is an entirely plausible premise. Advances in genetic engineering have dramatically lowered the technical barriers that once protected humanity from such threats. Meanwhile, the rapid expansion of high-containment laboratories around the world – more than one thousand were built in the United States alone during the five years following 9/11 – inevitably increases the opportunities for accidents or misuse. Whether or not Covid ultimately proves to have originated from a laboratory in Wuhan may be debated for years to come, but the possibility of laboratory accidents can no longer be dismissed. Jacobsen’s fictional lab leak is uncomfortable precisely because it is so believable.

As the author clearly explains, deliberate biological attack differs fundamentally from naturally emerging disease. During Covid, unprecedented international collaboration allowed scientists to sequence the virus quickly and develop vaccines at remarkable speed. In a biological-warfare scenario, those advantages disappear. The perpetrator is unlikely to disclose the engineered genome, forcing scientists to identify and characterise the pathogen under immense time pressure. Jacobsen’s most chilling insight is that the manipulation of an already familiar organism, in this case plague, could defeat existing vaccines and medical countermeasures. That possibility is far closer to reality than many would like to admit.

In 2018, the Johns Hopkins Center for Health Security ran a pandemic modelling exercise known as Clade X. In that scenario, a terrorist group released a deadly virus with the aim of reducing overpopulation. The purpose of the exercise was to test the decision-making of the participants, who included several people prominent in national security and epidemic response. Its conclusions were sobering: 900 million deaths were projected. It highlighted how rapidly governments become overwhelmed once transmission accelerates and critical infrastructure begins to fail. Jacobsen uses these realities to reinforce the credibility of her fictional account.

Throughout the book, she moves seamlessly between narrative and analysis, illustrating just how exposed many Western nations remain. Considerable lessons were learned during Covid, particularly in surveillance, diagnostics and genomic sequencing. Technologies now exist that could identify emerging pathogens in near real time, allowing outbreaks to be contained before they become global crises. The challenge has never been scientific capability; it is political will. Once the immediate danger passes, many governments prove unwilling to invest the relatively modest sums required to strengthen long-term preparedness. In the United Kingdom, for example, establishing a truly global pathogen surveillance capability would have cost a fraction of the economic fallout of the pandemic itself. Against the consequences Jacobsen describes, such investment would appear extraordinarily cheap.

The uncomfortable truth is that biological weapons remain the least regulated of all weapons of mass destruction. The Biological Weapons Convention (BWC), which was signed in 1972 and entered into force in 1975, prohibits the development, production, stockpiling, acquisition or retention of biological weapons. However, the treaty does allow for ‘defensive’ biological weapons research. Governments rightly devote enormous resources to nuclear deterrence, chemical weapons verification and non-proliferation regimes, but comparatively little attention is paid to strengthening the BWC or ensuring meaningful international oversight of rapidly advancing biotechnology. That imbalance should concern us all.

COVID-19 should have been the defining wake-up call for biological security in the 21st century. Jacobsen’s book argues convincingly that, in many respects, we have already begun to forget its lessons. One can only hope that policymakers read this work of strategic warning with the seriousness it deserves. The general reader, too, would gain much from this book. Annie Jacobsen succeeds in making complex scientific and security issues accessible without sacrificing accuracy or pace. Biological War is difficult to put down, but it is even harder to stop thinking about once finished.