A 27-years-old female with multiple autoimmune disorders presented to our cardiology unit for acute chest pain and worsening dyspnoea. Admission blood tests revealed increased serum levels of high-sensitive cardiac troponin, eosinophilic count and C-reactive protein. Laboratory findings, low QRS voltages by ECG, mildly reduced left ventricular systolic function in the context of pseudohypertrophy, mild and diffuse late gadolinium enhancement associated with markedly increased native T1 and T2 mapping levels assessed by echocardiography and cardiovascular magnetic resonance imaging, raised the suspicion of massive eosinophilic myocarditis, subsequently confirmed by histological examination of endomyocardial biopsy. Prompt initiation of immunosuppressive treatment allowed swift regression of myocardial inflammation and full recovery of left ventricular systolic function within one month. After ruling-out clonal myeloid disorder, lymphocyte-variant and reactive hypereosinophilia, the young lady was eventually diagnosed with idiopathic hypereosinophilic syndrome. This case report turns the spotlight on the role and importance of advanced multi-modality cardiovascular imaging for raising clinical suspicion of acute eosinophilic myocarditis, guiding diagnostic work-up and monitoring response to treatment.