Clinical decision-making process is very complex and influenced by multiple aspects. As diagnosis likelihood assessment is often based on intuitive thinking, data misinterpretation, and diagnostic errors may commonly occur. We present a peculiar clinical case of a 27-year-old obese woman admitted to the emergency department after an inaugural episode of seizures. She had an oncologic disease. She was febrile and hypertensive at first evaluation. The report evolves around the diagnostic assessment, hampered by incongruent anamneses, incorrect data interpretation, and a pinch of clinical obstination, which nearly culminated in two deaths. Then, we discuss the series of biases that have confused the physicians. The only way to escape the intuitive thinking trap is to be humbly aware of our own thinking method's limitations and to learn about the biases that often lead us into errors. Sometimes, thinking outside the box is the key.