Genomic analysis can be used to reconstruct outbreak dynamics; however, transmission chains of slowly mutating pathogens, such as Mycobacterium tuberculosis, can be difficult to determine because of low genetic diversity between isolates. Lee et al. used deep sequencing at 10–20 times the depth of previous analyses to investigate a tuberculosis outbreak in the Canadian Inuit. Earlier work had shown two distinct clusters of cases whereby isolates differed in a single nucleotide polymorphism (SNP), but no link could be found between the two clusters. Deep sequencing has now revealed that one patient actually harboured both strains, the one with and the one without the SNP. Based on this result and epidemiological data, the authors conclude that the most likely explanation is a super-spreading event in which this patient infected up to 17 other individuals, giving rise to the two clusters.