Metastasis after surgical resection of primary tumors is a frequent occurrence, and methods to prevent this are needed. Babes et al. demonstrate the utility of invariant (i) NKT cells in preventing liver metastasis. State-of-the-art in vivo imaging techniques show that repeated activation of iNKT cells with α-galactosylceramide (α-GalCer) increases their number and granularity in the liver, leading to inhibition of tumor growth and improved tumor immunity of metastatic tumors. The imaging approach serves to optimize how iNKT cells could be activated to induce antitumor cells for future therapeutics. The data also highlight a potential early intervention strategy to prevent, and/or treat patients who develop, liver metastasis. Read more in this issue on page 12. Original image from Fig. 7D. Artwork by Lewis Long.