The low abundance of many transcripts has limited the analysis of transcriptome complexity. To gain further insight, Mercer et al. used array-based capture followed by high-throughput RNA sequencing on human fibroblasts, achieving nearly 5,000-fold coverage of the small (~0.8 Mb) portion of the genome analysed. They found novel spliceoforms of both the tumour suppressor gene TP53 and of long non-coding RNAs (lncRNAs), such as HOTAIR. They also identified pervasive, low-level transcription of regions that were considered to be intergenic and could detect transcripts present at less than one molecule per 1,000 cells.