The Invisible Assassin
How tone hijacks your thoughts, decisions, and the world you create.
Available 5 November.
In The Invisible Assassin, forensic psychologist Dr Nashater Deu Solheim reveals how tone, working beneath conscious awareness, affects the nervous system and shapes judgement, relationships, and decisions. Tone can build trust, calm conflict, and bring people together. It can also close minds, distort meaning, and lead us towards choices we believe are entirely our own.
Not only are we affected by tone, we are also emitting it all the time. In our homes, workplaces, and public life, the signals we pass between us help co-create the trust or tension, openness or division, that follows.
Drawing on psychology, neuroscience, negotiation, and decades of studying behaviour, influence, and performance — including her most unexpected classroom, a dolphin pool where there were no words and nowhere to hide — Dr Deu Solheim makes this hidden force visible. Through the 4 Tonal Signals and Attunement Circle, she shows how to read what is shaping you, resist what works against you, and choose what you co-create.
Once you can see the signal beneath the words, you cannot unsee it. And everything changes.
Before you have time to weigh the words, tone is already shaping whether an interaction feels safe, believable, threatening, or true. Tone can make a stranger seem trustworthy, a leader sound convincing, a friend’s voice bring relief, or a politician’s speech stir loyalty or fear.
Available 5 November
Available soon at Barnes & Noble
“Most people prepare what they will say. Almost nobody prepares what they will transmit.”
“The assassin does not need to lie. It only needs us to stop checking.”
Reviews
Books
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How tone hijacks your thoughts, decisions, and the world you create.
The most powerful influence in any room is often the one nobody notices: tone.
Before you have time to weigh the words, tone is already shaping whether an interaction feels safe, believable, threatening, or true. Tone can make a stranger seem trustworthy, a leader sound convincing, a friend’s voice bring relief, or a politician’s speech stir loyalty or fear.
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The Leadership PIN Code introduced a practical framework for influence, negotiation and shaping outcomes between people. It gave leaders tools. But it also pointed to something deeper:
People do not respond to words alone.
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The ABC Workbook is the hands-on companion to The Leadership PIN Code. Where the book gives you the framework, the workbook makes it yours.
Frequently asked questions
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The Invisible Assassin is a book by Dr Nashater Deu Solheim about tone — the most powerful influence in any room, and often the one nobody notices. Working beneath conscious awareness, tone affects the nervous system and shapes judgement, relationships and decisions. It can build trust, calm conflict and bring people together. It can also close minds, distort meaning and lead us towards choices we believe are entirely our own.
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Anyone whose work, relationships or decisions depend on other people — and especially leaders. We are not only affected by tone, we are emitting it all the time. At home, at work and in public life, the signals we pass between us help co-create the trust or tension, openness or division that follows. The book shows how to recognise those signals and take responsibility for the ones you send.
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They are the two practical frameworks at the heart of the book. Through the 4 Tonal Signals and the Attunement Circle, Dr Deu Solheim shows how to read what is shaping you, resist what works against you, and choose what you co-create. Drawn from some of the most extreme environments she has worked in, they apply directly to leadership, teams and business culture.
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The Invisible Assassin is Dr Deu Solheim’s second book. Her first, The Leadership PIN Code, introduced her framework for persuasion, influence and negotiation in leadership. This book goes deeper — into the signals that travel between us and around us, shaping everything before a word is spoken. It stands on its own, and also works as a follow-up for readers of The Leadership PIN Code.
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From more than 30 years in some of the most demanding human environments — maximum-security prisons, crisis negotiation rooms, elite sport and boardrooms under pressure. The book draws on psychology, neuroscience and negotiation, and on Dr Deu Solheim’s most unexpected classroom: a dolphin pool, where communicating without words showed her tone operating as a pure signal.
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The Invisible Assassin is published by Amplify Publishing on 5 November 2026 and will be available everywhere books are sold. It is available to pre-order now, including from Amazon and Barnes & Noble.